That's massively over-simplified.

No, it's really not. Racism is either wrong, or it isn't. There's not a middle ground here. That not all incidents of racism are equally bad does not mean any incident, large or small, of racism is not bad.

And, unfortunately, sometimes correcting for past discrimination can itself involve discrimination.

There's nothing more permanent than a temporary solution, as the saying goes. That is precisely why all solutions, even imperfect ones, must be built on solid principles. Affirmative action, for example, is built on solid principles (unless one is some right-libertarian market fetishist, but fuck them), because it seeks the integration and inclusion of all races, even though it currently predominantly benefits non-majority groups. It seeks a better world, a world where people aren't treated differently based on who their parents or grandparents were. Racism based on the idea of inferiority is far worse than racism based on the idea of collective ethnic guilt - but both are still bad. Racism based on collective ethnic guilt is worse than racism based on a simple but fundamental 'othering' of a racial group - but both are still bad.