Yeah, I appreciate the attempt to laugh it off, but that was an awful joke. Not even remotely funny.
That said, if it were me, I would've probably been too embarrassed (and, if I was the CEO of Microsoft, totally incensed) to say anything at all.
It was a funny incident though.
I know a lot of Apple and FOSS fanboys who think Bill Gates getting pumpkin-pied is funny, but I didn't. That was wrong. This, however, isn't. Bill Gates is an extraordinary person; Steve Ballmer is a cross between a human being and an ape.
I'd sure like to see someone try to pull this stunt off in a Jobsian keynote.