>Basically all of the really classic comic book characters were made by Jewish people, they were a huge part of the industry.
>Is this cause for alarm? That's a genuine question. […]
Sure, a particular genre or art-form being culture-bound is no big deal. I can appreciate Islamic architecture or Chinese cuisine without being Muslim or Chinese. But Rationality is supposed to be universal and objective like mathematics or physics. That's the promise that attracted me, at least. I think it's unusual for any objective science to be culture-bound in this way, and so if something is, that casts doubt upon its objectivity unless some other explanation for the culture-boundness is found.
For comparison, consider medieval Scholasticism. Thomas Aquinas & friends thought they were doing "objectively true" philosophy. But when you find that it was only European Catholics who were promoting the ideology, that would make you question its objectivity.
>Is it really so hard to believe that a similar mechanism could extend to certain industries or professions?
No, but rationality is a worldview, not an "industry" or a "profession." In order to apply this analogy you would need to argue that "pundit who explains technical topics to a general audience" is an "industry/profession" that is predominantly Jewish for historical reasons. I suppose there's an argument to be made here. But while the set of people who write pop-sci stuff may be disproportionately Jewish, I don't think it's >90% Jewish like (evidently) the subset of those who expound the rationalist ideology in particular.