I think the Sam thing was inevitable, if not with Sam, then it would've happened with someone else. Ian's ego was off the charts, he thought he was smartertest person in the room always and the "puppet master" until he decided to make a hit piece on someone who wasn't totally retarded, an easy target or a low hanging fruit and everything crumbled down.
I didn't watch the airsoftfatty documentary, but from the clips i've seen Ian just exchanges smug, mocking looks with his cameraman like "look at this fucking retard". Zero empathy or actual interest in the target of the documentary, just a desire to make fun of someone and jerk himself off over how smart and cool he is in comparison.