I used to be a lot like that. Eventually I realized that I'll never reach my full potential as a male until I grew a pair. I still haven't fully but I'm working on it.
He may have low self confidence deep down. I know the reason I acted like that was because I didn't think I was cutthroat enough to act like a man or attractive enough to get away with acting manly.
Another big part of it was my lack of a decent male role model. That's not to say my father wasn't there, but he was kind of a nice guy/beta male/notgoingtogetintoargumentsoverterms. I grew up with my mother being the aggressively dominant figure of the house and thus I had the "in order to get women, I have to think like a woman." You can guess how well that went over. Long story short, none of my female friends at the time respected me.
I honestly pity males who act feminine because I know from my life that sometimes the guy was deceived into thinking that femininity was best, either because his parents taught him that or because he feels that he needs to lay low like that to survive.
I have a coworker that is femi like that. I know he isn't gay BC he has a wife n kids. Man he was walked on at work like crazy. All the gag drama queens like to bitch about "alpha" but to an extent the concept is alive and well in the corporate world.
In know a guy that has does that feminine hand gestures and sometimes talks like that but he checks out girls like any straight guy and has been down on girls before but he does a lot of gay jokes which piss of me and my friends I sometimes question his sexuality but I haven't said it to his face
I'm kinda like that too actually, although I can be sexually attracted to guys, but I only really like being in a relationship with women. If you're worried that he's gay / doesn't like girls enough, I would say you shouldn't worry about that because he probably isn't. Most gay males I've met aren't that feminine honestly. It seems possible that he could come out as a trans woman though like you said, but not necessarily by any means. Are you straight and/or would that bother you? If it would, you should probably ask him about it and if he's ever considered it, let him know up front however you would feel about it.
Only time will tell his true nature or why he acts like that.. have u tried asking him about it? If u like him go for it but he may not like u back the way u would want him too? What type of girl aee u? Can u handle this type of "guy" with all his female traits? What if he makws u feel like ur dating a girl instead of a boy? As a girl what about men turns u on? Can this guy do that sincerely? Is he in the closet? Sounds like a long shot too me but its up to u