Even if Graham supposedly booted Altman from Y Combinator, I don't see any reason to assume that a similar disagreement would have occurred in this case. Citing that history also seems to assume that Graham himself is an impeccable judge of character. And we don't necessarily have any reason to believe that. Seems to me like they're swinging at windmills with this narrative.

Given that the board provided very few details about their reasoning, the ideological divide seems like the most likely explanation because it's the most nebulous by nature. Also likely given the climate of hype/doom surrounding ChatGPT.