Just got the layout of the media-day podium assignments for the Seahawks, and of the 16 players allotted places, Marshawn Lynch is not listed. Other players will be assigned "standing" areas, so it's possible Lynch will be on hand but in a lower profile. I've been to most of the Super Bowls since 1992 and can't recall a star running back not at a podium.
There's been debate whether Lynch would participate, and NFL.com posted a speculative story. Lynch already had a $50,000 fine for not fulfilling league-mandated media obligations held in abeyance pending his further compliance. To be a no-show at Super Bowl media day would cause that to kick in, and surely draw additional penalties.