But they didn’t say, “We will do and we will hear.” They did not accept His authority, may He be blessed. I also command the people around me to massage my feet, but those insolent people are not obedient. People submit to the authority of the king because of his coronation (or the coronation of his predecessors). So the command has content because we poured binding content into it by accepting the authority of the one who commands. How is the Rabbi presenting things this way?

I already wrote here that acceptance from below is not necessary with respect to God’s command. Especially regarding the basic laws of morality, like the seven commandments, it is binding even if they did not take it upon themselves (the Holy One, blessed be He, takes Cain to task for murder before he was commanded and before there was anything like Jewish law even for the descendants of Noah). True, there is the matter of “He arose and transferred their property to Israel” (Bava Kamma 37), because they themselves withdrew from this, and seemingly there is here some de facto recognition of their decision, but I can’t go into it here.

You didn’t understand me at all. I’m saying that for us, Judaism was the revelation at the giving of the Torah in the presence of an entire nation, and therefore from our side the command is valid.
They did not receive any revelation at all, only a tradition that this is what Adam was commanded, so I’m asking: how did that validity hold up?

Are you sure I didn’t understand at all, or just not completely? 🙂
I repeat: they had a command, and by virtue of that they are expected to fulfill it. If they do not believe the tradition they received and also ignore the moral intuition implanted in them, I do not see why they should not be judged for that. Of course, if that truly is their position, then they are coerced by their own understanding and exempt.
As I wrote, a moral obligation needs less grounding in order for people to accept it. It is planted within us in conscience and moral intuition. Maybe that is why there was no need for an impressive, mass public event at the basis of these commandments.
Besides, the revelation that was given to us also included the seven commandments, and now they are supposed to observe them on the basis of the revelation at Sinai. And that, after all, was public and mass. Maimonides writes this explicitly at the end of chapter 8 of the Laws of Kings; look there carefully.