He probably already is and just look at his expressions when jun touches him or the way he blushses ╥﹏╥(≧∀≦)
It pisses me off, too!! Like "YO, I don't care how pissed you are at Kang, don't freaking call him that ya ass! Plus why tf don't you remember him telling you he was gay forever ago and you being totally cool with it?! You didn't seem drunk then!!??" (<--I'm literally confused by that part; why doesn't Siwon remember that?)
I get pissed everytime siwon call jinha a gay bastard. Dude trust me you will be one soon, Siwon