Extremely tiny probabilities with enormous utilities attached do suffer from Pascal's Mugging-type scenario's. That being said, AI-risk probabilities are much larger in my estimate than the sorts of probabilities required for Pascal-type problems to start coming into play. Unless Perrr333 intends to suggest that probabilities involving UFAI really are that small, I think it's unlikely he/she is actually making any sort of logical argument. It's far more likely, I think, that he/she is making an argument based on incredulity (disguised by seemingly logical arguments, but still at its core motivated by incredulity).

The problem with that, of course, is that arguments from incredulity rely almost exclusively on intuition, and the usefulness of intuition decreases spectacularly as scenarios become more esoteric and further removed from the realm of everyday experience.