BasicIncome

It's not different from race in that regard.

The basis of the legal challenge is on the law saying you cannot discriminate against protected classes, race, disability, gender, etc.

There isn't a specific rule preventing affirmative action, taking steps to mitigate prior discrimination, from happening, but in practice, there is often enough an argument that can be used, that helping a disadvantaged group is still discriminating against another group.

While I support UBI and affirmative action in general, there's a very real chance this will lose a court battle.