Because what he did and said is literally the dictionary definition of coercive control - a recognized form of domestic abuse that is illegal in the UK and in several US states. It is not boundary setting. Getting into a relationship with someone and letting them get attached before you start limiting their independence and their autonomy is coercive. Limiting where someone can go and who they can talk to is always abusive. So is telling your partner what they can and cannot wear. As you pointed out, if he didn't like the way she dressed, he shouldn't have dated her. But he did like the way she dressed - he just wanted that only for him because he felt insecure that other people also found her attractive.
Conversely, if I say that I don't ever spend time with people who treat me rudely, that's not about you - you have the right to be as rude as you want, just never around me or I'll leave. If Hill had said that he doesn't date surfers, or he doesn't date women who wear bikinis in public 🙄, then that would have been a boundary - a misogynistic and ridiculous boundary, but a boundary nonetheless. Instead, he loved that she was a surfer, that she was a model, loved a picture on Twitter of her sticking her butt out in a bikini while surfing - but then wanted to possess and control that person who attracted him. Not cool and incredibly toxic (to say nothing of weak).
As I wrote in another story, if you don't trust your partner, why are you even with them?
