And if it weren’t monetary, then no?
The Torah said that a debtor is allowed to pay with inferior-quality land. Requiring him to pay with average-quality land is like instituting hand-washing. There is no obligation here at all; there is a permission from the Torah in this matter (even if that permission is not explicit in the Torah), and a rabbinic obligation.

Seemingly, the whole rule that property declared ownerless by a religious court is ownerless applies to actual property, but in our case the money/property is not the issue. The issue is the proper form of payment to a creditor, since the Torah established that the proper way to repay a debt is with inferior-quality land. So what connection is there between court expropriation and the form of payment?

Shetef,
Without the monetary aspect, there is an infringement on the borrower’s right to pay with inferior-quality land. That is an uprooting through positive action. Simply speaking, it is like instituting that he must pay him two hundred instead of one hundred.

Abba,
I don’t understand why that matters. They can declare his superior-quality or average-quality land ownerless.

So the Sages did override it through positive action?

Yes.

And is it really so obvious that the limitations of positive action versus passive omission apply also to the enactment itself, and not only to its fulfillment?

I didn’t understand what the difference is.

Rabbi Michi, according to your approach that it all depends on court expropriation, I don’t understand what exactly the court is declaring ownerless in this case???

Two possibilities:
They declare his average-quality land ownerless.
The ability to declare property ownerless gives them the authority to require him to give it, even without actually declaring it ownerless.

I don’t understand how it’s possible not to understand the difference. Positive action deals with the person himself at the time when he obeys the enactment, not with the sages’ power to shape Torah laws.
Here is the language of the Talmud in Yevamot 90b:
“Come and hear: Blood that became impure and was nonetheless sprinkled—if done unintentionally, it is accepted; if done intentionally, it is not accepted.
But here, where by Torah law it does procure acceptance, etc., and the rabbis said it is not accepted, he ends up bringing unconsecrated meat into the Temple courtyard.
Rabbi Yehoshua ben Levi said: What does ‘it is not accepted’ mean? It means with regard to permitting the meat to be eaten, but the owners did achieve atonement [and do not need to bring another offering, Rashi].
In the end, the eating of the meat has been uprooted, yet it is written: ‘And they shall eat those things by which atonement was made for them,’ etc.
He said to him: Passive omission is different.”

And from here two proofs can be brought.
A. According to you, already when the rabbis said that it does not procure acceptance, they uprooted through positive action by changing the characteristics of an existing legal status-object, even if he does not bring unconsecrated meat into the Temple courtyard. Clearly, then, the problem is the bringing of unconsecrated meat into the courtyard, not the enactment of the Sages itself.
B. Rabbi Yehoshua ben Levi answered that the eating of the meat is uprooted by passive omission. Why is uprooting the obligation to eat the meat not considered uprooting through positive action? Is changing the characteristics of a right, such as the borrower’s right to pay with inferior-quality land, more of an uprooting than changing the characteristics of an obligation, such as the priests’ obligation to eat the meat?

That I understood, and I still think the two collapse into one another.
I seem to recall that the Turei Even at the beginning of Chagigah discusses diminishing from “do not subtract” or “do not add.”
Uprooting an obligation to eat is passive omission. If that is positive action, then everything is positive action. Expropriating property is positive action.

The logic for the distinction depends on how one understands why the sages do not have such power. To challenge it on the basis of the intuition that there is no distinction—rather than as a springboard to some elegant answer, but simply by leaving things at the familiar understanding—seems strange to me. Though on second thought, precisely because the answer doesn’t innovate but only leaves things at the familiar understanding, one is not too bothered by weak objections.
Still, the proofs are not clear to me. If you wrote about this from the aspect of the sages’ authority, I’d be glad for a reference (I didn’t find it on the site). And with your permission I’ll return to them.
A. Why is declaring “acceptance” ownerless not positive action until he brings unconsecrated meat into the Temple courtyard (as the Talmud and Rashi emphasize)?
B. Indeed, in every case of passive omission as well—if we discuss it from the standpoint of the sages’ enactment itself (and not from the standpoint of the person’s act), then why is uprooting an obligation different from expropriating property? Because in the case of the obligation they prevented it from taking effect, while in the case of a right they changed something already existing?

I explained that in my view positive action and passive omission depend only on the person’s act. When a person takes money that is not his, that is positive action. I don’t understand what problem you see with that.

Rabbi Michi, at the beginning of the discussion you wrote two possibilities for the enactment of average-quality land based on court expropriation:
They declare his average-quality land ownerless.
The ability to declare property ownerless gives them the authority to require him to give it (even without actually declaring it ownerless).

Regarding the first possibility: it is a major novelty to say that repayment of a creditor is not really repayment from his own assets, but rather that the court declares part of his assets ownerless and repays his creditor by means of that ownerlessness and not by ordinary repayment.

Regarding the second possibility: an even greater novelty than the first. Do you have a source for such an expansion of the authority granted to the court by virtue of court expropriation?

If I’m being accused of innovation, I’m willing to plead guilty. But here my hands are clean. There is no special novelty here.
A. You are misunderstanding the concept of court expropriation. Court expropriation is a mechanism that is implemented by later people. The property does not become ownerless at the time of the expropriation, but at the time it is paid. For example, when the sages institute the legal mechanism called “the presence of all three parties,” the document/debt is not acquired at the time they made the enactment (in the time of the Talmud), but when the relevant people carry out that mode of acquisition. Court expropriation merely makes this possible contrary to Torah law. A nice expression of this principle is found in Rashi on Bava Metzia 96b regarding misuse of sacred property by a husband with respect to his wife’s usufruct property (“the court of that generation are the ones who commit the misuse”); see there carefully.
B. That leads us straight to the second possibility, and now you will understand that it is not really so different from the first. But the logic underlying it is nothing more than the rule of “it is in his power,” which is widespread throughout Jewish law even for an ordinary person, and certainly for a religious court. There is no special novelty here. See my remarks on the approaches regarding admission of a litigant and self-imposed prohibition, which view them not as credibility but as a vow or undertaking. There too I explained that this cannot be the explanation; rather, it is a mechanism of “it is in his power”: https://mikyab.net/%D7%A9%D7%95%D7%AA/%D7%A9%D7%95%D7%99%D7%90-%D7%90%D7%A0%D7%A4%D7%A9%D7%99%D7%94