Question

Hello Rabbi,
Following up on the last lecture on simplicity, the Mishnah in tractate Berakhot says:

1:1 From when may one recite the Shema in the evening? From the time the priests enter to eat their terumah, until the end of the first watch; these are the words of Rabbi Eliezer. But the Sages say: until midnight. Rabban Gamliel says: until dawn rises.
1:2 It once happened that his sons came back from a banquet and said to him, “We did not recite the Shema.” He said to them, “If dawn has not yet risen, you are permitted to recite it.”
1:3 And not only this, but wherever the Sages said “until midnight,” their commandment extends until dawn rises. The burning of the fats and limbs—their commandment extends until dawn rises; and all offerings that are eaten for one day—their commandment extends until dawn rises.
1:4 If so, why did the Sages say until midnight? Rather, in order to distance a person from sin.

But regarding the commandment of matzah, Maimonides writes:

“It is a positive commandment from the Torah to eat matzah on the night of the fifteenth, as it says: ‘In the evening you shall eat matzot’ (Exodus 12)—in every place and at every time. This eating is not dependent on the Paschal offering; rather, it is a commandment in its own right, and its time extends throughout the entire night.”

At first glance, it is difficult: why, with the commandment of matzah, did the Sages not enact that it must be eaten by midnight in order to distance a person from the sin of neglecting the commandment to eat matzah?
In addition, in the commentary of Rabbi Ovadiah of Bartenura I saw that he explained:
To distance a person from sin—that he should not come to eat them after dawn rises and become liable to karet …
That is, the concern is not neglect of the commandment to eat the offering, but that he may come to eat it after its proper time and incur karet. If so, it is difficult why, for the Shema, they decreed that it should be recited by midnight, since here there is no concern of eating notar or any other transgression if one comes to recite it after its time.
And I thought perhaps to resolve both difficulties as follows: what the Sages established—that the time for the Shema is until midnight—is not because of distancing from sin (since there is no transgression here), but because that is considered the time of lying down according to the view of the Sages, somewhat similar to Rabbi Eliezer’s view, except that they extended the boundary of “time of lying down” a bit further. And when Rabban Gamliel said that one may recite the Shema after midnight, that is in the sense that in pressing circumstances one may rely on my view. And when the Mishnah says, “wherever the Sages said until midnight, their commandment extends until dawn rises,” that refers only to things where there is concern of an actual transgression, such as eating notar, but not to concern about neglecting a positive commandment such as Shema and matzah. What do you think?