Isn't it great that these people live in a country where they can express their opinions? They actually think that anyone outside the US cares about their opinions. When you see the photos, you'll understand the mindset better.
Don't bother trying to respond. As the webmaster (?) says "I've also received a bit of hate mail. I would lampoon these people publicly, but the type of person who sends hate mail to a website is generally too easy of a target. Anyway, hate mail is how you know you've made it. Keep it coming, guys."
As I said, don't respond and give them any ammunition. They are young and just haven't grown up yet. Give them ten or fifteen years and most of them will see the light.