I bet you Tenacious D had at least a small something to do with John Reilly's name on the lineup.
I was going to say that his being signed to Third Man Records has more to do with it, but given he's playing on Monday per the TMR website (the same day Tenacious D is performing) and Jack White is performing on Saturday, there absolutely is no reason John C. Reilly should not appear as Sasquatch.
Got to see this madness. It was truly spectacular. The man even got a fuckin police escort. There are really no words to describe how amazing his new show is. I hope he brings both the girl and boy bands to Sasquatch.