Political conflicts were always a risk for Substack. The problem with it is that it's not a matter of choosing between (say) Nazis and anti-Nazis, when a scenario like this plays out they lose both the Nazis and anti-Nazis.

Worst of all, Substack gets almost all its revenue from literally a handful of popular blogs and any of those people can hook up a payment gateway to a bulk email script and stop paying a cut of their subscription revenue to Substack... Thus they are highly vulnerable to pissing those people off and losing them and a political kerfluffle is a great way to do that.