Finally got a chance to listen...
This was always my reading, too. After all the build-up of the battlesuit (which has, of course, a fly), which was so long that it went from being funny to being overdone all the way back to funny again, Mxy cackles with glee at finally having the upper hand, and is gone for all of three seconds before he returns. He's barely gone long enough to say his name backwards, let alone anything resembling a fight. And, IMO, it's much, much funnier that way.