This doesn't seem like a big mystery. It would not take a smear campaign or some kind of major boycott to cost a company that became too closely associated in the public imagination with alt-right whackjobs.
Too closely - meaning having a customer that said the N-word somewhere? I'm not picky, just trying to understand what "too closely" means in your answer.
The threshold that would have to be crossed - that was crossed, unless someone at the company took a decision to ban the guy just because he's obnoxious, which is possible - would be for the company to feel like its future earning potential were at risk because of reputational damage. I doubt the judgment on the part of the company is going to be as simple "a single user said one specific thing." How could it be?
Very interesting statement, considering that Sargon (the guy Patreon banned) was directing his offensive language AT the alt-right (i.e., he is against the alt-right, not part of it).
If you say so. My statement could be amended to include "and people even batshit crazier than the alt-right."