That article does not seem to claim that point in it. Maybe I just missed it. But I checked all usages of high, population, city, and cities, so if the point is made in that article is is done so with different enough language to be difficult to find considering the article's length.

Edit: That all means I am calling bullshit on that being a citation for that fact (or 'fact' depending on your view of it).

That article is atrocious as any kind of source, it's clearly an opinion piece.

I'm asking for an actual study comparing homeless rates of liberal cities vs conservative cities. Also a list of which cities are actually liberal vs conservative would be nice.