That wasn't suggesting he's gay at all. It was blatantly stating that he doesn't want to be in a relationship with anyone, he just wants to observe people who are.
Upon first exposure, I believe that his intentions are good, and for his own enjoyment from the outside. Of course, you never know. I like that he was so forward about it though and that he didn't dawdle.
Kinda creepy. I'm worried that he's going to pull some cliche "If I can't watch/be the only one to watch, nobody can!" and the manga would force some unneeded drama.