Role-acting that conflates lack of info with skepticism. If you're acting out the role of a dutifully skeptical scientist, you say that things are a long way away unless you have strong info that they're about to happen, for fear of making a mistaken prediction that makes you sound like a mere enthusiast. Failed negative predictions don't count against the role - they don't reduce your prestige to that of a mere enthusiast. Just imagine it as a serious frown vs. a childish smile; they're trying to give a serious frown, and avoid childish smiles. You're dealing with a behavioral rule for when to agree with verbal statements, not a coherent state of uncertainty. Both "we know very little about the future" and "AI is fifty years off" sound like a serious frown, so they agree with both.

I doubt there's very much more to it than that.