Nothing questionable that Mozilla does can affect the forks, as long as the forks have enough manpower to sustain themselves. There are, in fact, a few examples of projects with questionable leadership getting abandoned by their userbase, as everyone migrates to the fork.

I think what you need to worry about is whether the fork you’re using has enough momentum and developer time that it’s going to stay alive. That’s a concern whether or not you have a concern that the central leadership is going to do something obscene.