I didn't perceive it that way at all.
Finn has been trying to straddle the in crowd (i.e. football, jocks, etc) and the out-crowd (glee). And his way of not alienating himself from the in-crowd (anymore than glee itself) has been to look/act/etc "normal" and fit in with the in crowd's style. This was even pointed out specifically when he yelled at Kurt in the bathroom for dressing and acting different.
So him dressing "weird" was all about him willing to do something different and freaky rather than sticking with the status quo fashion. More about trying to apologize to Kurt by willing to be different when he had just yelled at Kurt for not dressing like everyone else.
Anyway, just the way I took it. I didn't see anything to suggest Finn "turning gay."
