Wrong but worth arguing with- or simply nonsense?
Nonsense of course.
Because we all have multiple loyalties- to entities both large and small.
One simple example: if I were a Catholic (which I'm not) I would owe loyalty to a transnational organisation as well as to my country. In favourable circumstances those loyalties would be complementary and not in opposition.
Anyone who has seen the pictures the first astronauts took of Earth from the vicinity of the Moon- (and that's most of us)- knows what it is to be a citizen of the world. There's our planet- small and not big, suspended in the darkness- our home- and the heart goes out to it. But having that feeling doesn't cancel out our loyalty to the little bit of the planet where we happen to live. Armstrong and Aldrin and Collins didn't cease to be Americans because they'd seen the planet whole.
When I was a kid we used to write our addresses inside our school books- and the trick was to make them as long as possible. Mine went something like this:
Anthony John Grist
23 Croham Valley Rd
If I were doing that now- because I know more than I did in the 1950s- I'd add Multiverse to the list.