While McMahon, as a conservative, may actually be peeved at the NFL for how it handles the national anthem issue, there is clearly a profit motive here. McMahon believes (maybe right, maybe wrong) that many NFL fans are also conservatives, Trump supporters, etc. and that they will be attracted to a league that takes a stand, that plays on nostalgia for a "traditional" brand of football and that plays up the jingoistic "Patriotic" card. I am sure that to a point he has that right, but then his choices of cities make even less sense.
They make no sense from a media standpoint. Placing teams in cities that already are packed with major league franchises (all 4 sports) is already a questionable move, but if his target audience is more conservative, 'Murica types, he would be far better off looking at Birmingham, Orlando, Texas or other Red-State locations. Putting teams in LA, NY, Seattle, DC makes no sense if you want to attract that demographic and then you add on top that no TV station in any of those markets has time to cover XFL games because of all the other teams they need to cover, and I don't see this as a recipe for a successful league.