@yabaibunni I don't mean to butt into the conversation but it seems to me that you're misunderstanding some things here
1) ono is utilizing homophobic rhetoric in order to hurt jun. it doesn't matter if he's a villain or not or if he was hurt and this is how he's lashing out, Ono is ostracizing and attacking Jun using homophobia. he's able to pit the entire class against jun by spreading rumors about jun's sexuality and then using their ignorance//naivete//prejudice to fuel the fire. Ono knows that the remarks he's saying hurt, he knows he's being a nasty person (as you can tell with the last panel how he has regret and hesitance on his face) and
the way he chooses to hurt Jun is through homophobic remarks. You can say he's homophobic here, because instead of creating animosity towards jun for cheating on his girlfriend, or trampling on the feelings of his best friend, or being an all around
shitty person to the people around him,
Ono is shown to be attacking Jun for his sexuality, attacking Jun for his sexual experiences (remember in chapter one Ono received praise and power from sharing stories of his sexual encounters with his girlfriend, he knows that the sexual status of the boys in the class will affect their social power because he was directly benefited from it). Ono has been aggressive towards Jun for a majority of the series (bc of the situation with miura), and he lets go of that aggression and justifies it through homophobia (smth like "jun is a bad person because he cheated on his girlfriend
with a MAN" not "Jun is a bad person because he cheated on his girlfriend")
2) Jun absolutely can be homophobic. Internalized homophobia is a thing. By the looks of it, Jun does not have any healthy relationships with other queer people. his best friend (mr. farhenite) is an HIV/AIDS recipient/carrier. And jun met him, and established a relationship with him, through that (knowing he has a stigmatized terminal illness). Jun doesn't have an allies, he's navigating through this world blind. From his environment and all his friends it's safe to assume that he lived in a pretty isolated and openly homophobic/ignorant world. He doesn't have an LGBT support system. He doesn't have anyone too confide in that accepts him as an individual first. You can have a future as a Gay person, you can have a family you can have kids you can blah blah blah, and I know that because I was able to see it through LGBT role models and elders.
Jun doesn't have those. He is struggling because he doesn't have anyone that can give him assurance of the future as a positive role model (he really only has the guy dying of AIDS, the dude he's basically having an affair with, and the lesbian bar owner who is fine with jun and makoto's relationship despite a whole plethora of things that shouldn't make it fine).
3) and he chooses to distance himself from others by feeding into their prejudice, because he's scared more than anything. if he's vulnerable and nice but still gets rejected he'd feel even more awful. like he's doing everything right but everyone still hates him. Jun thinks that if he plays into their ignorance and acts the way they expect a "nasty homo" to act then they're justified in cutting ties with him. He doesn't want to be rejected, but he knows rejection will happen, so why not be a bitch. I don't think it's the best way to do things, in fact I think it just is stupid he reacts like that, but also he's a teenager and his best friend/confidant committed suicide. He's not in the right state of mind. I think he's using his sexuality to confront others because he'd rather be rejected as a "homo" instead of as "andou jun" and when they do reject him, "the homosexual," the rejection just further fuels his internalized homophobia and makes it harder for him to escape that narrative/understanding.
