The explanation is that this scene takes place in an inter-dimensional prison, filled with the worst convicts across the multiverse, alternate Eggmans, alternate evil Knuckles's, one panel even showed an evil alternate Cream. The Mephiles pictured is likely one from another universe.
Seriously there are a ton of cameos and parodies, from the images I've seen theres an evil Big, a muscle bound Amy, an Angry Birds bird along with Bebop and Rocksteady.

So he literally travelled from an alternate timeline just so this joke could happen?