One of the things I've learned reading about cults along the way is that, for the most part, no outside stimulus makes a difference. Outside opinions are perceived as personal attacks and only solidify their world more as a defense mechanism. When the leader is punished or even criticized, he is a martyr. It is a completely isolated and insulated ideological ecosystem. Either they wake up on their own at some point or they don't.
This isn't about politics for them. This is deeply personal. It's about who and what they are. Imagine: They'll allow this to destroy their own family. Just like any cult. So in some ways, that makes this even stronger than their religion, such as it is. And/or a replacement for it.