That's odd, Lindsey always struck me as a very sexual being.
He likes to perform without his skivvies on, loves to simulate bedroom noises on-stage, writes songs about...you know, and is rarely found without a half-way open shirt.
I've watched the Mirage video over and over and over through the years and never saw one ass cheek. Stevie doesn't strike me to be the kind that would go without undies, that's Lindsey's arena. Thank god his fly has always stayed zipped up.
The only problem with the argument that it's because of Stevie's butt cheek that it never was put on DVD is that it's already been released on video. If there was a butt, it could easily be edited out. Also, the band would have no say in whether it got released again; they don't own the rights, Sony does and Sony is not affiliated with their record company at all.