I don't really see the constituonal basis here. Racial discrimination is explicitly prohibited by the Constitution, so there's an obvious angle for calling affirmative action unconditional. That doesn't really exist with legacy admissions.
It's still stupid and shouldn't be a thing, but it's not the job of the Courts to ensure an optimal college admissions system. Saying that it's de facto racial discrimination is a pretty big stretch.
Activists sue Harvard over legacy admissions after affirmative action ruling ( www.cbsnews.com )
A civil rights legal group is challenging legacy admissions at Harvard University, calling it racial discrimination.