Troublingly, I think he actually does think these ideas are helpful. Is a True Believer any less dangerous?

"Sufficiently advanced incompetence is indistinguishable from malice."

I think True Believer is worse. I would say that if someone is willing to try something while still willing to accept that it might not work but need to confirm they'd be a rational person. A True Believer will not accept that the thing is not working and try to rationalize why others are still wrong.

They are generally dangerous but they are truly dangerous when what they believe is itself dangerous.

I'll be using that