There has been a controversial push in California to reform public school math education guidelines called the California Math Framework [1]. It [2] frames current math education in California as failing minority students and gives suggestions for how to remedy it. The issue has been controversial as some see it as injecting social justice topics into the math curriculum, while others see it as necessary to contextualize math within our broader society. (edit: corrected by the other reply to your comment that said some of the parts of the framework about adding social justice topics have been removed from the most recent draft of the framework)
The tweet author is pointing out that this 800-page framework about addressing inequalities in math education for minority (in particular Black and Latino) students was written by many authors, but none of them were Black. This seems like a valid criticism given the issues that it is explicitly trying to address.
There have also been similar criticisms levied at the new framework because it was written entirely by academic researchers studying pedagogy and had little to no input from actual teachers.
[1] https://calmatters.org/education/k-12-education/2021/11/cali...