I think it's a pretty clear-cut issue. The guy has said some despicable things. The devs had the option of removing him from their game and distancing themselves from what he represents. They didn't. Even minimizing his role in the game to a single line that can be easily missed is not enough.
For the record, people can feel as they do but the JonTron stuff is way, way, waaay blown out of proportion. The devs minimized his role a lot so he literally only has one line in the whole game that's missable. He also gets no money from sold copies of the game anyways, so buying it does not support him.
You are either giving him a pass or you're not. And the devs of that game are giving him a pass, so they are not having my money :)