Define "threatening". It's a slippery slope. Yeah, maybe "Allahu Akbar death to America" is an obvious one, but what about "Fuck Trump for pulling out of the Paris climate accord" - is that "anti-American"?
Name one country that will grant you VISA if you start yelling similar things about their president.
If we start seriously saying "but it's okay for China to do it, why not us!" we've already reached terminal velocity sliding on that slope.
And phrases that might be critical of the President, but not enough to deny entry?
I'm curious to know where you see the line between acceptable and unacceptable...
They're not insecure about themselves, as societies, the way America seems to be lately. So sensitive!