Considering my own experiences working with Python (specifically Python's tooling, the language itself is nice), I would posit that "lack of engagement" is a good avenue to explore... Python programmers probably swear less in their code and commits because, by and large, they're victims of abuse that have learned not to expect much joy in the first place :P

As much as I've enjoyed this article, I find it hard to believe that we could get meaningful statistics out of the code we have access to. There are many factors that dictate whether a dev might push swear words into a codebase, I'm guessing that a primary factor for that would be maintaining a veneer of professionalism. Personally, if I was going to curse into the ether I'd probably confine it to a private repository. Or write up a Medium article about my experience, in which I might not swear, but may perhaps make a scathing observation or two :)