First, so I know that you read it, I'm going to repeat what I said earlier. At some point, you have to look back at this conversation and think "I got really fucking aggressive just because this guy said a date differently from how I do, and it makes me look like a twat."
Second, more important to my point, USian is not my demonym, and you don't get to decide that it is. That's really all I should have said this entire time.