IQ isn't the right metric. It's important, but you shouldn't fetishize it, because it mostly acts indirectly. You can get away with tabooing IQ and intelligence a lot of the time.
The quality of your inside view depends on your knowledge about the relevant topics, your skill at evaluating evidence, your intuition for it, and a number of related skills and intuitions. All of those are largely acquired, and not all of them are fully general. Intelligence correlates with how easy it is to acquire them, but not perfectly.
Looking for a threshold is silly, because a good Bayesian knows 0 and 1 aren't probabilities. Looking for a general factor is silly, because your inside view on microbiology is worthless if you don't know anything about microbiology, no matter how intelligent you are. Invoking IQ is silly, because it's only a proxy for more informative directly applicable skills.

IQ is just another factor you may or may not want to take into account when taking the outside view. For example, "students with IQs over 130" and "students" are reference classes that give you different answers for "how likely am I to graduate?"