I for one cannot be convinced that these companies saying they want to slow down AI progress is for the safety of mankind (or any other altruistic reason). However, I respect someone willing to give up a very comfortable career for his convictions.
I’d wait and see what happens next in their professional life. It’d be ironic if they founded a new AI startup or something like that.
That most people are sincere in their beliefs (in AI doom), as the author says and I think too, doesn't mean there aren't cult leader-types exploiting these beliefs. And their private beliefs may be quite different from their stated ones.