It's not about the "Gap in Math", it is about ideology with regard to social justice, withdrawing support from gifted children, removing difficult topics. They don't want to help kids catch up, they want to make sure nobody can get ahead. The Backlash is not against helping out "poor" kids, it is against hampering the progress of talented kids.
100% This.
I thought that was what “closing the gap” was. In fact, in the podcast “Nice White Parents”, they’re explicit about that. It about preventing advanced classes and tutors so the achieving kids can commingle with the struggling kids.