Read the opinions of the Court. This is out of control judicial activism. The court ruled that the specific case, brought by some older police officers, had no validity. But it ruled that, in general, you did not have to prove intent to be biased. The 9 mullahs should only have said whether the case was valid or not. Instead, they went beyond that to make up a new law.
Oh please. All eight Justices agreed that any claims would be strictly limited by RFOA (Reasonable factor other than age).
And as for your claim that they just decide the specific case -- true enough, but they have to first interpret the law and decide what the specific intent is before applying that reasoning to a result. The eight justices came to three different comclusions on the interpretation, but ended up with the same result in the case.
I get the feeling that some folks see judicial activism much as some saw Communism in the Fifties -- yes, it exists, but we won't find it in every decision or under your mother's bed.