Unless you've got some raws to point to where something actually happens, it's not yaoi. Though I'm not convinced that such an event isn't looming in the immediate future after this chapter... Except for the fact that, this is in a shounen magazine. Nobody's seriously going to allow gay sex on-screen, I think it's safe to say.
Could add a shounen-ai tag, I suppose. Generally one doesn't add those when it's just a gag, but given that it seems to be the central gag at this point, it's an arguable case. Though I'd personally be inclined to wait a few chapters and see what the gag : fanservice/romance ratio turns out to be before making that call.
@pokari @penghibur2 @monkey123
any manga with 'gender bender' has shonen ai and shojo ai to some extent.
except maybe the oneshot where a t-rex has been reincarnated as a girl, but that one doesn't count.
The pedant in me is compelled to point out that here, the gender-bend is a completely different issue from the gay. Different characters entirely. Indeed the gender-bent character isn't romantically involved with anyone, in any sense, at the present time...