Yeah there really is. His voice is so deluded and propped up by effects, that even if the tone of his voice didn't match the album, or he kinda sorta missed a note here or there, you wouldn't be able to tell.
It's not like it's particularly hard to sing either. He probably sang it really well, and the effects did the rest.
And as someone else mentioned before, there's no reason for him to lip-sync it. They could easily just play it pre-recorded. The fact that Mike even bothered to sit down on stage is proof to me that he's singing it, along with the other reasons I gave.