The Simpsons shocks with Katy Perry oral-sex joke

This week's episode of The Simpsons ended with a remarkably provocative joke involving skeevy bartender Moe Szyslak (a registered sex offender!) giving oral sex to not-especially-musical, yet bosomy, pop star Katy Perry. In another attempt to switch things up, the episode also featured the Simpson family reimagined as Muppets for some reason, so Perry actually played herself instead of just lending her voice. The joke:

[Moe attempts to kiss Perry, but can't reach her face, because he's a three-foot-tall Muppet]

Moe: I'll just kiss your belly-button.

Perry: Oh, that's not my belly-button! ... But I didn't say stop.

Shockola! Was this a tangential reference to the Katy Perry Sesame Street controversy? Or part of an ongoing campaign to enrage Bill O'Reilly (a notorious hater of puppet-sex and other comic perversions)? Who can say?