Is your last claim a joke or serious? Because anecdotally I've seen almost the exact opposite in my social circles. But of course that's just personal experience.

I think it is a reference to a study earlier this year that found that vaccine hesitancy was greatest among PhDs: https://www.usnews.com/news/health-news/articles/2021-07-27/...

>most anti-vaxxers have advanced degrees and above average IQ

I find this deeply implausible, both from first principles and personal experience. Can you back this extraordinary claim up?

This study shows a negative correlation between IQ and covid vaccine hesitancy: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8133799/

Why is IQ an acceptable measure HERE but any other use of IQ correlating with behavior is shot down?

The parent asserted a correlation. I contradicted it. Neither of us explicitly cited IQ as a "measure" of anything, but also I expect neither of us would object to doing so in broad strokes. So you'll have to find someone else to ask.

About 22% of americans identify as antivaxxers, and about 13% Master's and/or doctorate and/or professional degree. For your claim to be true, over 90% of people with advanced degrees would have to identify as antivaxxers.

That is, if words mean things to you. If what you intended was "I feel like anti-vaxxers are smart, and want to come up with a fancy fact-like way of saying that," then you're spot on. good job sport.