Actually, I thought the author was making a completely different point. Clinton excused his behavior by accusing the right (often falsely) of acting the same way. The author is not excusing Lott's conduct and is quite explicit about that.
Rather the author is pointing out the hypocricy by the left and it's media organs. They go hysterical about Lott and ignore the N word by Byrd and ignore Fullbright's history when Clinton gives him an award.
The point was that the left's PC hysteria is not motivated by any real concern for PC. Rather, it is a weapon to be used selectively to silence opponents and to gain political power.
That said, Lott spoke inappropriately and we should not be hypocrits. When one of ours misbehaves, we usually take him to task, eg Richard Nixon and now Trent Lott.
There is the issue of "Will this argument work?" But there is also the issue of truth. Lott didn't mean it the way Jesse Jackson and others are choosing to take and exploit it. I think that's the point in exposing Clinton. Not to get anyone off the hook or say "they do it too." Rather, the point is to say "Clinton was not endorsing segregation and neither was Lott."
Do you see what I am trying to say? I hope. (I can be articulation challenged sometimes, lol.)