I would say Horner looks EXACTLY like the type of boss you wouldn't want to have that does mobbing. I mean he looks quite intense and quite arrogant and he thinks he knows it all because he holds the power. So, if some smaller level employee did something he didn't like, he probably "abused" as in like yelled and threw stuff and so forth.
This is still a quite terrible thing and yet it is so normalized in society that we do not see that as a problem, we just warn him and move on and he tries to control himself a bit more, loses himself a bit again time to time but tries to be better. It is of course not as terrible as abuse in other sense, that would be disgusting, but I really doubt that would be the case, it is just bullying because he is a real bully, we can see that.
I'm very sceptical about this kind of stuff, things like #meToo and similar. Nowadays it's easy to ruin someone's reputation, and even if you're innocent, it still leaves mark in your reputation.
If it wasn't sexual harassment, it would be interesting to know what exactly was that "controlling beheaviour". Not defending Horner and not saying that boss can do whatever he wants and whatever he likes to his employes. But in general, some people nowadays are soft like snowflakes and you can't tell anything to them.
It looked that everything goes almost perfect for Red Bull, it would be shame if team will collapse in this way.