If other non-humans like Samandriel have the same emotional reaction as the others, I'd say that makes him eligible to at least hear the music even if you don't want him to get too swept up in things! Peter's supposed to be a grossly overpowered little shit in OUaT terms, but his focus will mostly be on keeping out people who don't belong there.

HE'S TOTALLY WELCOME TO COME PARTY IT UP WITH THE YOUNGSTERS. Gross, though, Adam might have more reason to see that even angels have feelings. HOW TERRIBLE. X(