I think it's a harder case to argue. I'm sure the law as written doesn't say "white rascists who murder blacks"... Even though that IS how it is enforced. Selective enforcement should make it unconstitutional, but I think that's harder to argue, while the thoughtcrime aspect should be a slam dunk against the First Amd.
Why do I think it's harder? Take affirmative action as used by the governments. Not as advertised, or in theory, but as implemented: racial and gender quotas in hiring, promoting and firing. These laws are written to treat people differently. This is blatantly in violation of the 14th, and yet the laws have been around for a long time. And being written is more clear cut than just being selectively enforced.
Plus, you have to gather all sorts of cases where the h-c law is selectively applied.
I think that adds up to being a harder argument than straight freedom of thought.
Brian Bronson