That's not the underlying reasoning and I have heard very clear arguments. The argument goes something like 'the extremely impactful event has never occurred in the past so our risk assessment is very vulnerable to large magnitude errors'.

What is encouraged is taking actions that have well understood OR bounded risk.

By bringing up "concern-trolling", I am concerned you have given up the fight. By avoiding the direct argument and retreating to this supposed hidden argument, which is much easier to counter, there is not anything left to discuss. Tell me if I am misunderstanding.