For the record I mostly agree with you, but those other things necessarily require twisting the centrists' arms, which means hitting them where it hurts (votes being one of the more obvious targets). To unpack the metaphor, putting all of one's political capital into slower fascism naturally means that little to none of it will be going to no fascism; for example "implement this policy I want or I won't vote for you" is a classic way to force politicians to do things but it's impossible to pull off if your ultimate priority is preserving the slower fascism coalition. You can remember the Palestine protests for what that looks like in practice, but the short of it is that there are things you can't do if you decide you're never going to publicly oppose the centrists.