I think most people, including myself, aren't miffed about this being an US meetup, but more about the point that the thread is written as though that is the only place on earth.
OP mentions "several states away" and the coasts without ever saying it's an US meetup beforehand. Even the title doesn't specify it.
I'm sure there were no bad intentions, but with the way the post is currently worded it just confirms the stereotype that US citizens think that the US and A are the center of the universe. All that was needed was to say it is an "US meetup" and it would have been fine.
There's a reason so many people joke about US artists' world tours being every state and then 3 performances in some random outside countries.
Just because I dislike how the post was worded and mention as much doesn't mean I don't want everyone participating to have fun though