When I am in a foreign country, their flying their own flag, or singing their patriotic songs bothers me not in the least. I suspect our flying our flag, reciting our pledge, or singing our songs bothers foreigners not in the least.
If it is Americans worrying about what non-citizens think, their hypersensitivity is misplaced. If they themselves are offended by other Americans love of their own country . . . they deserve less respect than they give those whom they call non-PC hate-speakers.