Yeah... There is a lot more context there than "he wouldn't take no for an answer"... But you go ahead and ignore EVERYTHING else. The conversation they were having RIGHT before the sex about how Oono has been using Kureshima as delusion material means nothing, the dialogue at the end of chapter 4 of Oono stating "This feeling, i pretended not to know. I yearned to be touched again. I intended to blame him. Reality was much better than delusion", none of that matters. The implication is that he was in denial and didn't actually hate the sex, he was just lying to himself. It's also heavily implied Kureshima knew Oono was in denial, hence the conversation and sex in ch 3 as well as Kureshima's dialogue in ch 4 saying "you know why" when Oono asks why they had sex. He knows Oono is in denial, the point of the sex was to make him face reality. Kureshima went into having sex knowing Oono is in love with him and didn't stop because they both knew it was consensual, albeit "deep down" on Oono's part. I.E. "dubious consent", as you said. No need to look farther into it than that. I feel like you either missed or ignored all the context involving Kureshima and that's why you hate him, but if you just read ch 3 and 4 with the knowledge that Kureshima knows already that Oono loves him, but is in denial, i think a lot of that confusing dialogue might make more sense to you. Oono alludes to Kureshima's "insight" TWICE in ch 3, "Kureshima scares me, it's like he knows everything", "i don't understand Kureshima, he scares me". The 1st quote he literally SAYS it, the 2nd quote he's admitting that it feels like Kureshima understands something, or has some kind of knowledge, that he doesn't and it scares him. The "insight" is that Oono is already in love. In ch 3, when they got to Oono's room, why did Oono get embarrassed and apologize for starting to undress in front of his "friend" Kureshima? He's already sexually aware of him even before the sex.
I think we can all agree that this was at least Dubious Consent. Which means during the time of the sexual act the Uke was on the fence on whether he wanted to participate in the sexual act or not. He was probably in between.
However, this in between does not excuses the fact that he clearly voice 'No' and was ignored. So, the seme is a shitty person who does not know how to take 'No' as a answer, or even know that he should take 'No' as a answer (This I will blame on the writer/artist for this horrible character).