As usual, I agree with my waifu Basement Cat.
The problem with the Dorian/Bull relationship is that it's so vague and so unexplored, we don't know. Sure, you can come up with all the rationale and explanations you want, and they can make total sense and be a consenual, happy relationship that has no abusive or gross elements, but you can also easily read it as something uncomfortable and upsetting.
If I had a friend who was in a relationship like that and I couldn't make sure they were okay with everything, and that this was making them happy, and all I could hear was the snippets I heard with Dorian/IB, I'd be worried. I wouldn't be judgmental if I found out they were perfectly happy and it's what they wanted, I would be happy for them and enjoy their happiness. But I'd want to be sure first, and you can't do that here, so the "bad" reading of it that people are getting is just as valid as the "good" one. Being able to ask Dorian about it would have gotten rid of that issue, but it didn't happen, unfortunately.
I think we would all have a better discussion about this if we acknowledged that there are multiple possible readings and the ambiguity of the text doesn't allow us to agree on one, because then we could untangle it without yelling at each other and accidentally saying offensive things.