Specifically because AA cannot be, by the US constitution, be written in a racist way.
99% of the way AA in America is used is not in a racist way. This Harvard case is just giving African Americans and Latinos the exact same privileges as Whites.... it just left out Asians and other groups. Which it shouldn't have.
If you stop Harvard from doing this new policy, the OLD policy is still racist. The case has fixed no problems
And, more importantly, a win in this casw has given a win to actual racist. Because now only Whites get those privileges