I've always thought that I'd be fine with his confession going either way, and I still do now. It's not like Ishigami would have gained nothing from all that. He'd have gained a lot in his pursuit of Tsubame (good grades, working out, the rumors about him are negated), but this chapter was super damning in favor of getting rejected. Even if she starts seeing him as a man now, it's definitely too late for that. She's graduating and going off to university and has been burned once by someone she was in close proximity to. I can only imagine she'd be pretty poorly fit for a LDR right now, especially since Ishigami's actually kind of popular.