I disagree. I think anyone can learn anything, though it may take an unreasonable amount of time and effort for some. Learning a new concept can be complicated, especially for things introduced in high school and university. All those concepts rely on others, so those lemmas have to be learned first. I do believe some people are generally quicker learners than others. But it's a continuous scale, not a yes/no thing. And interest in the subject plays a big role.

For a metaphor of education, I'd say people are like Turing machines. (A) If there is one person who can learn a concept, then any of them can; (B) some are faster than others; and, (C) the "optimal in practice" state is usually limited by need and not capability (i.e., using modern laptops too just check emails and browse the web).

>but saying this in higher education circles is akin to burning a Koran in Mecca.

I'm not a fan of preemptive impersonations of Copernicus. I'd rather read what people said and judge that.