I don't disagree; I just think that the idea of "thou shalt not violate the player's agency" as a "commandment" is overstated (and uses a definition of "violates agency" that is at odds with how I and others understand it). In that regard, there are times and places where the idea of "the player controls (every aspect of) their character" is supposed to be infringed on by the DM. This includes areas where aspects of the character are undefined, and the PC wants to define them in a way that is favorable to them when an ambiguity arises (which, as you alluded to, is often when something has already happened...or in some cases, is in the process of happening).