I think the problem is that Jonathan Haidt has been getting too much uncritical press treatment. At some point it’s natural for him to start believing the hype and then just spouting off on whatever.
I’m a big fan of descriptive research. Causal inference is fine, but you’re gonna get into trouble if you try to come up with theories to explain purported facts that aren’t actually true.
P.S. Haidt’s article also features this charming bit: “Across many kinds of surveys, in the UK as well as in the USA, we find that people who self-identify as being on the left score higher on questions about care/harm. For example, how much would someone have to pay you to kick a dog in the head? Nobody wants to do this, but liberals say they would require more money than conservatives to cause harm to an innocent creature.”