A person you respect in one field is not necessarily all-knowing within that field and, most certainly, not outside of it. This is especially true on topics that become politicized. This is not just because of the 'our side' vs 'their side' stuff, but because these issues can and have destroyed the careers of high profile people who adopt the wrong opinion.

Unlike the individuals you have cited, James Watson is a geneticist, spent his entire life studying and working on genetics, and in fact was even the person who discovered the structure of DNA. But because of his views on the genetic aspects of IQ (which inherently becomes intertwined into race, as race is just shared genetic ancestry), he was completely demonized, his career destroyed, and various honors revoked. Higher profile people speaking on these topics publicly know this all too well, so it mostly just turns into cheap virtue signaling as opposed to adding some genuine insight.

In your case, the examples they've offered are simply wrong, as would be immediately apparent with the most typical method of measuring heritability!

You're irritated because I gave you an output of the broad-sense heritability statistic that conflicts with your intuitive understanding of what "heritability" means. Now you understand how people feel when commenters randomly throw around the term "heritability" with respect to cognitive ability.

This is a "not even wrong" situation. Is cognitive ability significantly genetically determined? Maybe, maybe not. A broad heritability statistic from a twin study isn't going to resolve the question.

Here's a good link for you:

http://bactra.org/weblog/520.html

I promise, the author has studied and thought more carefully about the question than we have.

Fair warning: you would not be happier if I cited a molecular geneticist on this subject. Your argument gets even harder to sustain once you bring GWAS into the picture.