The Rationalists are a philosophical/pseudo-religious organization in the same way the Daoists are. Just spending a lot time thinking about something doesn't make them right, it just makes them internally consistent with their chosen axioms. That is useful: if you agree with the axiomatic beliefs of such a movement, you can probably defer a lot of reasoning about the conclusions of those beliefs to the authority figures within that movement. But it doesn't change the probability of the axioms themselves being true, any moreso than the Pope saying so affects the probability of God existing.
AI Is Important And Potentially Dangerous is an axiomatic belief in the rationalist circles that are relevant to AI safety, in the same way that God Exists is axiomatic to Catholicism.