There are a good number of people who enjoy both ships, me being one of them. Though I guess the definition of "ship" is to say, "This is the one important couple/relationship to me and the only thing that matters to me in the whole fandom, and every obstacle to that relationship is a despicable character blah blah blah..." I won't even describe how liking both at once works for me, because I'm sure it's different for everybody; I'll just say I also don't know how somebody could get through the whole show only supporting B/M because Brian and Justin's love is beautiful and surprising and disarming and undeniable, in its own time. Anybody seeing only what they wanted to see would have been thrown off their illusions by mid-season two.