Bisexuality has such a bad reputation unfortunately.
I myself "was bisexual" before i told myself i was indeed gay. So yeah, it can be used as a stepping stone and it does give you some sort of social normality by saying you're into both. That doesn't mean someone else isn't genuinely interested in both genders. Since when did some speak for all?
Society wants us to be black or white or in this case, gay or straight. Some people don't fit into either and that's fine. Saddens me to see gay people diminish other's sexualities as fake or fibbed as homosexuality in general is claimed fake by people all the time.
However, maybe Shane is gay. Maybe he's bisexual. Either way, hope he finds happiness out of this ordeal.