He used a very old quote in an off-handed quip that fell flat. It wasn't an attempt to be or say a serious thing. Was it in poor taste? Sure. Would he like the moment back? I'm betting he would. Have most of us said something we wish we could unsay? Of course we have.Really, what is the big deal anyway? So old men say silly things. Who cares?
Is much being made of little? Yes. A lot of people were upset when they learned about his affair in 2009. Strangely, most of them weren't morally outraged by his not being married to the woman he stepped out on...life, people. Go figure. That was 2015. What's happening this year and with people who are actually in a position to impact the popular culture? Letterman is already an afterthought. That's how it works.