@Insignificant:
If it was as you say, the tag cross-dressing tag would be nixed, too.
To the best of my knowledge, the lack of a shounen-ai tag in a case such as this is based on the fact that, outside of fan-service, nothing definitively gay has happened (yet):
A) It wasn't (and technically still isn't) totally clear that they'll end up in a relationship (a peril of this genre has always been—though less so these days—that the author could chicken out at the end and leave things open-ended so as not to upset any delicate and insecure straight men who don't want it to get
too gay), so it's not clear that there's going to be a romance between two men here.
B) Neither clearly has a one-sided gay crush, either: It's not clear that Kobinata has feelings for Chiroda (because of deliberate and even sometimes perhaps ham-handed ambiguity meant to build suspense), and while Chiroda clearly has some budding feelings, it's also clear that he isn't even convinced Kobinata is a boy.
How much these shades of grey matter varies depending on who you ask; but I'll be weirded-out if it isn't clearly shounen-ai by the end given the way the story's been going lately.
(P.S. Forgive me if I'm reacting seriously to a shitpost, I don't know what your reaction image was supposed to be before it broke.)