Muhly, who lives in a Chinatown loft with his cat, said he is less snobby about writing for an organization like the Pops than he might have been in years past. In fact, he spoke to Keith Lockhart on the phone, and contrary to the “complete nightmare” he expected, he found the Pops conductor “charming, smart and funny. “He was really great talking to me about Messiaen. I had an out-of-body experience.”