Uh... what? Performance outcomes differ between racial groups in mandatory classes all the time. If the argument really is that "disproportionate impact" in classroom outcomes is enough to render a policy unconstitutional, then your only option is not to measure outcomes at all, because every educational measure shows differences between races.
I edited the quote above to contain the court's entire statement from the finding, because it's even more damning and removes the possibility of a less absurd reading. Apparently the justices know absolutely nothing about education and race because they don't know that "racialized teacher candidates might disproportionately fail these math courses" is exactly what we should expect, because that's exactly what we find in every other educational context.