Out of curiosity, why shouldn’t his personality come into it?

There’s no moral or ethical basis to not consider his personality when evaluating Twitter, and even if you have one I’m not obligated to share it.

You don’t have to understand things for them to still be valid! To me, he’s an offputting guy doing a bad job, and those two things are valid to consider when thinking of his company according to my moral values. That’s subjective, but it’s clearly a view that many share with me.