It was a joke. I mean, it's a joke I personally happen to believe is true, but not something I will state as factual.
Somewhere on the political spectrum lies objective facts, truth, and logic. My priors tell me this side tends to be left-of-center. My priors also tell me that the majority of people's political beliefs are decided for them by their parents and their upbringing. So I'm happy to admit that plenty of liberals are in it for the wrong reasons. That doesn't detract from it being the side on the correct side of history.
I also used to believe that facts and truth were left of center. But after the whole "get vaccinated or you will be killing someone's grandparents" propoganda came out to be false, I have a hard time believing the left.