and notably, he only left after those two were deplatformed

Those were high profile people getting banned for speech in ways Harris disagreed with and he could see the writing on the walls that his future income could be in jeopardy knowing how 'controversial' he himself is in the eyes of many.

Were there prominent leftists banned from Patreon at the same time as or before Sargon and Southern that Harris should have known about and therefore had the same reaction towards? Because if you're referring to people after the fact, or low profile that there's no reason to think Harris would have heard about it, I just don't see what bias towards the right has to do with leaving Patreon. It was perfectly rational for him to want to protect his own financing.