That's somewhat oblique, easily attributed to misunderstanding (I'm not sure what actual question was asked - it's been a decade since I saw Revolution OS), and poorly thought out: a "Red Hat Linux" system at the time was running more GNU code than Linux code (and overwhelmingly more than Red Hat code).

Every damned other thing in there seems to argue precisely the opposite.

I defy you to find anything Stallman said (as opposed to characterizations by others, which could easily be deliberate or accidental mischaracterizations) that implies a position that a system without GNU code (or with insignificant amounts) running Linux should be called GNU/Linux. If such exists, then I will agree with you that Stallman once held the absurd position you attribute to him.

Edited to add:

"It came up in the documentary because there had been a huge firestorm over RMS saying everyone should call it GNU/Linux."

I agree that there was a huge firestorm over RMS saying everyone should call it GNU/Linux. I disagree with what that "it" refers to.