Should have been 20 yards in penalties. The offside is called and the play is dead the second Sherman makes contact with the right wingman on the FG formation (or when his move into the neutral zone forced that player to move). PF for unnecessary roughness then becomes a dead-ball foul, with the yardage added after the administration of the offside.
As far as Moss and the other ex-player apologists on ESPN's broadcast saying it wasn't a dirty play, Levy should have simply asked them what they would have thought had a defender taken a clear, running shot at their knees while they were in an exposed, vulnerable position.