...Not sure why a judge would look at it again. Was a third party arbitrator used? Yes...ok, then get lost. Don't come crying to mommy now that daddy has said no.
This process has been used before and the player was able to stay on the field for nearly a year until it was resolved. The NFL's decision isn't legally binding... it doesn't matter if they used a 3rd party arbitrator unless Gordon specifically signed something saying he would legally abide by the ruling. I don't think they even used a 3rd party. It was just the NFL front office.
The basis of the argument will be something like the NFL unjustly preventing him from earning a living, or grossly/detrimentally affecting his earning potential for the rest of his life, since it doesn't just impact this year (contract extension would be bigger if he played well again, etc.). This could be very interesting. I think there's still a good chance he plays this year.