After dropping $3.3mm maybe he thinks he has nothing to lose. I don't know, I'm kind of surprised he got as much a greg and Payton, because equating the penalty would seem to be equaling the authority, which wasn't the case since he wasn't a coach.
But the flip side of reading potential innocence into the ferocity of his response, is asking how the league would dish it out if they didnt feel confident they could defend the penalty against the NFLPA and beyond. Goodell doesn't seem the type to act without getting clearance from the lawyers first.