C)
If you're going to posit straw men, here's one with a steel spine: How about displaying the Irish flag on St. Patrick's Day? Does that make you disloyal? Or simply as proud of your ancestry as any Scotsman or Italian or Nigerian or Greek or Chinese or Polish or Japanese or Ukrainian or Indian...180 more countries to go, but surely you see the point.
This is what it means to be a "nation of immigrants" and a "melting pot". Immigrants have an ancestral home other than the US, and it's not "poor form" to acknowledge that.
Except, apparently, when it's Mexico. Why is Mexico an exception?