If it had more to do with the way his character specifically was written, as opposed to just being white-centric, then that would make more sense as to the timing. He also may very well have become more confident in voicing his opinions than he was in previous workshops.
I don't have any insider knowledge either, but based on the bits and pieces that we know, I'm more inclined to side with Stachel. At least until I get additional information to suggest otherwise (if anyone feels like sharing here, or PMing me, I'm all ears).
I agree it's possible that Stachel had legitimate concerns AND was a nightmare to work with for other reasons. But again, until anyone feels like sharing stories about why he's a nightmare to work with, I'm more inclined to think that he was "the problem" only in the sense that he was the one standing his ground on these issues.
EDIT: To clarify though, I do agree that there's obviously missing information here about what, exactly, was the nature of the dispute such that it got to this extreme point of contention.
Updated On: 10/21/21 at 06:07 PM