I trust that the people felt his behaviour was awful. If they don't like working with him, they can switch jobs. Or even complain to higher ups and what not.

What is not OK imo is this appeal to some imaginary "societal moral court" that should somehow punish the guy.

Why are you arguing that awful behaviour should have consequences for those it is direct at, rather than for the person who commits it?

I said they felt he is awful. Maybe he felt they are awful, too. It is a thing that happens in human relationships, that people end up disliking each other. We have only heard one side of the story here.

It is a pretty normal thing that people don't get along with each other, for whatever reason. Just because one party goes public and frames the other as a horrible person, doesn't necessarily mean they really are.

If nobody who is disliked by somebody could become boss, there would only be very few candidates left.

What, exactly, is the other part of the story that you imagine would make his behaviour not awful?

There was not that much context to the story to begin with, so it is unclear how awful he really was.

Yes there was. There was a bunch of people who say he is. That is context.