@Chrispykreme, BL is not precisely the kind of label that stops you from do what you want
"I used to think there was some sort of requirement for BL to be all lovey-dovey and have happy endings with a moderate amount of sex. (...) Other than the fact that it’s “a relationship between guys,” I discovered that it’s a genre where pretty much anything goes."
Harada (one of my favourite BL mangakas, be careful, they create really harsh works)
Having a bi as a protagonist won't make any difference on it being a BL, it will be more on how @CallMeMattheww runs the plot. Noone will blame a scifi queer story for being labeled on BL on a place like Tapas, cause that label is pretty much the place where everything minimun related with queer and LGBT themes end up.
The day Tapas allow to put more labels, the site will set on fire -evil laugh-.
No, now seriously, it may be difficult to label a story that doesn't fit with the prototype of a concrete label, but makes those labels embrace more variety enriching the label and its readers, showing that BL can be more than "two gay guys discovering their mutual love".
Let it be BL, but free above all, @CallMeMattheww