In any case, I don't see how we can actually use these considerations.

If you know how to build a uFAI (or "probably somewhat reflective on its goal system but nowhere near provably Friendly" AI), build one and put it in an encrypted glass case. Ideally you would work out the AGI theory in your head, determine how long it would take to code the AGI after adjusting for planning fallacy, then be ready to start coding if doom is predictably going to occur. If doom isn't predictable then the safety tradeoffs are larger. This can easily go wrong, obviously.