“evidence that shows all fifth graders are capable of eventually learning calculus, or other high-level courses, when provided appropriate messaging, teaching, and support (sic).

I've taught teenagers maths, and some teens remedial maths. Trust me, some can't learn much beyond basic addition and subtraction. I'd love to know what evidence supports that bullshit claim of theirs. I've literally one on one tutored kids who couldn't even figure out a bus time table.

This is basically Marxism infiltrating the education system. They deny innate ability varies by child despite decades of genetic research showing it does.