Why does it matter at all whether the choice is canon or not?
DougsLeftNut said that intervening with Alices boyfriend will probably give an in for rapid progress with her when we get back. And it might, it does give her a few points and creates a variable to track whether you talked the guy down or knocked him out. It also tracks if you just walked away from that encounter, which Alice might not be too thrilled with next time we meet her.
It's like any of the other dozens of choices in this game, either do it if you're interested in Alice or want to show off for Skylar, or don't.
Does anyone here ever seriously look at a choice that pops up in this game and think "Hmm which choice is the canon route?". I know I sure as hell don't, I pick the choice that makes sense to me, and will get me more points with the women I like. Which is ALL OF THEM in this game