Should we not think he's a piece of shit for berating and casually firing employees

There is a big gap between that and getting mad and not talking to someone for a bit.

At some point I think it's necessary to distinguish to what degree parts of his behaviour are expressions of neurodivergence and to what degree they're expressions of simply being a bad person who has no interest in anything except his own whims and desires.

I do distinguish that, and in this case it's the former. It seems like other people are not able to distinguish that and are instead attributing everything to the latter.