But TMTM was a movie. Even if the minister was real, it's still only a movie. One of the novel things about the movies is that the Muppets regard them as fictional (or "approximately true", in TMM's case) movies as well...
...ahhh, forget it, it takes too long to explain. Let me just say...TMTM is a movie. Kermit and Piggy are still single, and, though Miss Piggy often denies it, Kermit has no intentions whatsoever of ever marrying her.