It is. I'm sorry to burst your bubbles, but...
And I don't mean it was a hint, the panels CLEARLY implied it to the point where it was undeniable.
Not only that, but although some of the relationships can be passed off as brotherly/fatherly in general nature, there are still a nice handful of relationships in here that you can only call shounen-ai. Like Ayanami and that one guy who has a freakin fetish for him ("Aya-tan!").
I, personally, also can't see Teito and Hakuren's bond being "brotherly".....there were lots of things that made me say otherwise....
And on this series being shoujo, it's only "shoujo" because it has a main cast of bishounen and focuses on relationships rather than action most of the time.
However, if it's written like a shounen, almost looks like a shounen, and is freakin READ like a shounen, then it's a shounen manga in my book.