I wonder what Sondheim thinks of this whole thing and what Sondheim actually said.
I would have a slightly different take on Brown's main faux pas, which is looking a gift horse in the mouth. Someone whom he has never met has gotten him tickets to a show and is taking him out to dinner. (Brown says the tickets were Sondheim's "treat" rather than saying that Sondheim got him tickets, implying that Sondheim actually paid for the tickets for a complete stranger, not that it matters all that much.) Sondheim is doing a nice thing for Brown. The polite thing to do is to say when you sit down to dinner, "Thank you so much for the tickets! That was so nice of you!" Because it WAS a nice thing for Sondheim to do, and it should be acknowledged. Add a little bit more genuine gushing about how nice it was and what an honor it is to meet Sondheim, and Sondheim probably wouldn't have cared that Brown hasn't actually said anything about the show itself.
If your favorite aunt gets you an ugly sweater, you tell your favorite aunt that you like the sweater. Not because you're necessarily all that crazy about the sweater itself, but because you love the giver and what the gesture stands for.
Brown got a gift that he didn't like, from a complete stranger who had good intentions. You don't make that complete stranger who has good intentions feel bad about something that can't be changed. Brown didn't mention a gift he just got to the gift giver, whom he saw right afterwards, for twenty minutes, until the gift giver had to ask about it. That was rude. Really rude. Brown adds in all this stuff about "great art" and makes it seem like the anecdote is about the creative process, but I wonder how much of that is Brown and how much is what Sondheim actually said or felt at that time. I'm not sure the incident is as much about an artist having a fragile ego about his creative output as Brown seems to think.
"What was the name of that cheese that I like?"
"you can't run away forever...but there's nothing wrong with getting a good head start"
"well I hope and I pray, that maybe someday, you'll walk in the room with my heart"