Ask yourself, if the ACLU really believed in free speech, would they have given up so quickly? Nope.
It’s really simple.
They don’t want to be judged on the content of their character, they want to judge everything based on skin color and the idea that there are oppressors/oppressed. If you’re not the right skin color, you are an oppressor by default because of long past transgressions.
If we were to judge people on the content of their character like King thought we should (king of course being their icon), then they would wither away. They know the content of their character is irredeemably flawed and morally corrupt. Because of that, we must not ever bring it up lest we get at the root of the issue and people start to stray from the plantation.