I mentioned this to a friend earlier. Faber doesn't come off as someone who'd go with loyalty over a title fight against a teammate if he stands to benefit from it. Which isn't a bad thing, but in his case, makes him look like a dick if he does it.
Faber had a falling out with Ludwig after the Barao fight because he didn't think the training was sufficient. Which, I imagine, is due to him not improving a 1/4th of what the other UFC TAM members improved under Bang. He's hit his peak level of striking ability, which is fairly mediocre, so he thinks Bang isn't good enough. Or he's jealous of the other members improvement.