Rush just can’t wrap his mind around the fact that people think that what’s normal today hasn’t necessarily been normal for the last 100,000 years (a decent approximation of the age of the human race, actually; the planet’s just a little older).
It’s pretty much the opposite of social conservatism, which posits that what’s normal today is normal because it’s the best thing possible so it should never be changed (think Burke). Also, colonialism.
But heck, if he thinks that we should stop using our own lives as a metric of what’s normal or what’s good, I’m not going to disagree. Something tells me, though, that he isn’t thoughtful enough to take this philosophy to its logical conclusion.