That's something I had trouble understanding as well, and I think there is a lot to endorse it and also a lot against it.
Saki was very religious, that's pointed out by both Yasu and the previous game. And she didn't like Akira very much, why him though, and not Nozomu?
Now, for the Akira was gay theory, he used to pray every night while stuck in his bedroom, which probably means that he was suffering some sort of abuse, and it would make sense for a religious parent to not accept him being gay. This would double down if Nozomu was "normal", and already married with a woman - and maybe that would also fuel resentment between the brothers. And lastly the thing with the flowers is that "he" would destroy every flower so that no one could be happy either or that he'd destroy others as he was destroyed or something - and that fits very much with this background. Gay dude has his sexuality beaten out of him and develops an over macho persona to compensate.
Akira is also very against any idea of another dude being involved in his sexual acts, he threatens violence when Maki and Haruka suggests pegging him, and there are almost NO DUDES in this game, except for the fact that there are many of them (like the principal, Ayane's father, Touka's father, old man Tojo, Noriko's father, Kirin's father) he just blocks them all out.
Now for the against theory - first of all, it's very hard to not assign any reference to a "him" to Akira because he's the only real dude in the game. Maybe the reference here is to Nozomu, or even his own father. IF the Nozomu being the father of half the class holds water, then he'd be more likely to fit that description. After all, in terms of hiding his sexuality, Nozomu married Sekai, how exactly did Akira hide anything? Maybe they were pissed at each other because Nozomu's marriage was fake and Akira was the man he was supposed to fake himself as, including having his wife fall in love with (a wild twist would be if Nozomu actually was in love with Akira and jealous of Sekai for having her way with him).
The strongest piece of evidence however is that Akira already has a very strong background without it. Kid gets sort of assaulted by some random girl that asks to see his penis, goes on to be molested by his sister-in-law, eventually falls in love with her, she replaces his every value and becomes his world, he is broken when she's gone (cause he didn't create a persona to deal with his mother trauma, only relied on Sekai) - then Maya comes along and breaks him forever by having him "replicate" with her what Sekai did to him (Noriko seems to imply this by saying that in Maya's effort to fix him she instead broke him even more - during the 3rd DormWars) - all of this already seems like a lot without the gay angle.
Anyway, I still don't know how to take that piece of info but that's the same for a lot of LiL - I would say however that I don't think it's that relevant. If Akira ever had an interest in men that was before Sekai, and that would make him incredibly young. And if he had been assaulted by a man, I think the flashbacks we have from Sekai's first experiences with him would be different.
Sooooooo, what I think it means is that if it refers to Akira then it's some other stuff. Or maybe it refers to Nozomu who knows.