Concerning Mises and the opera, I once said, perhaps even at a formal Mises event, as a joke, that I oppose all government intervention, except that the govt should force everyone to read Man, Economy and State. I was trying to show what a moderate I was. I’ll bet that if it turns out that Mises said what is claimed he said about opera, it was a similarly minded joke.
I specifically remember Rothbard, also trying to show what a moderate he was, saying that, as a interim first step, he would accept George Washington’s budget for the US budget at present.