In my experience at European eateries, museums, churches, etc. German tourists tend to be even louder than Americans. And Ireland is one place in Europe where Americans tend to be especially welcome. But as someone already pointed out, his business and his rules. Beyond that the owner can just go F himself.
Sorry, but you’re emphasizing his point. “the owner can just go F himself”??? Really?? Maybe its just an elderly proprietor who prefers a nice sleepy pub for the town folk, and is tired of dealing with obnoxious Americans. Given your response, i’m now much more sympathetic.