I don't think you're seeing what the parent is saying. What you are suggesting isn't actionable. We already have legislation to make discrimination illegal and it hasn't been effective at stopping it.
Of course it is - the action is to stop discrimination of any kind. And yes, yes it has been effective. Hate crimes have dropped off precipitously and minority unemployment is at an all time low. Continuing to play this reverse-discrimination game will foment resentment, especially in the group that is "allowed to be discriminated against" according to the political flavor of the times (particularly the ones that aren't winning in society) thus creating the monster that you sought to destroy.
No, it's not actionable unless you've developed some kind of machine that can change other people's opinions.
You're right that we've made significant progress on racial issues. That doesn't mean more can't or shouldn't be done. Furthermore it's not clear from your slippery slope argument that the disadvantages of reverse discrimination (of which there are of course some) are actually more significant than the advantages.