(and also a liar, via the implication that you are not an American yourself)
This is a specious assumption. Being in a group does not mean a person is not willing and able to insult it. This assumption would make the world simpler for you, but the world is not this simple. Anyone with experience dealing with people knows that people do things that don't make logical sense all the time. All the fucking time. Quite often people feel like they are qualified and entitled to insult their own group because they are a part of it. This person is not necessarily a liar (for reasons inferred by your assumption).
No man is an island if he's on at least one mailing list.