I'm a bit lost about the point Thomas is making. Is it that we ought to stop singing old songs, or that we ought to make a point of rewriting them in a way that cleans up the past? And is there an assumption that in all respects the way we are today is better than the way our predecessors were?

If there are people who use old songs about ways of treating each other that have changed for the better, and do so as a tool intended to change things back for the worse, obviously that's a bad thing. I haven't come across it, but that doesn't mean it doesn't happen. (Though I can't see it as very effective in any case.)

As for "An Old Man Came Courting", that's both sexist and ageist - the two don't rule each other out; but I wouldn't dream of objecting to it. If it was a song about an ugly old woman and a young husband, I probably would - there's an inconsistency there, but I think I could defend it.

On the other hand I wouldn't have any regard for anyone who objected on these kind of grounds to a song like Rocking the Cradle.