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.
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.