My argument that leaving your home town is costly stands regardless of what your definitions are. For a similar example, tall people tend to both be more intelligent and to come from richer families because malnutrition as a child negatively effects both height and intelligence.

You may ask if I'm not using a pedantic, irrelevant definition of correlation that captures even tiny correlations we don't care about, but when we're talking about politics (where swings of a few percent can reliably flip elections), and polarisation (which is pretty much defined to be the amplifying of small differences), I think this is very relevant.