This is not, and cannot be, about "justice". What you mean (I think), and what the Union and protesters mean by justice, is some not entirely clear (nor universally agreed) definition of fairness.
In the Court system, justice begins by following the law and the rules of jurisprudence; not by some arbitrary, case by case, decision on what is "fair and just", or what the rules will be about how to run a trial, despite what the law (or in this case the CBA) says.
The minute you go that route, then there is no standard. Every decision that isn't what a player or the Union wants winds up before some Judge chosen according to what his personal "fairness" doctrine is.
Goodell, to me, is an ass. Can't stand the guy. But, the Union bargained to give him 100% discretion in handing out discipline in exchange for other provisions that were more favorable to the players. There is even an appeals process in the CBA and that process was followed. In fact, that is not even being challenged by the Union. The Union is trying to win based on "fairness".
How would you feel if the League went to court and said that it wasn't "fair or just" that teams could only practice according to some arbitrary, one size fits all, standard that the Union wanted and is part of the CBA? Why? Because it hurts rookie QBs especially; it hurts teams with new coaches and new systems; it's unfair to rookies in general who need WAY more practice time ........whatever. So even though the owners agreed and it is part of the CBA, the League wants a Judge to overrule it and impose it on the players according to the Judge's own sense of what is "fair".
Justice and fairness ought to play no role whatever in this matter concerning Elliott; what is just and fair is for both sides to follow the spirit and the letter of the CBA. However "fairness and justice" is what the Union wants to make it about because it is not definable; and there are hundreds of Judges who have made it their job (even though it's not) to approach their decisions in that way; essentially disregarding the law and precedent and putting their personal views above it all.
I can fully understand why the Union doesn't like the way it works right now. Fine. Then in the next CBA, bargain to change it. That's the proper way to go about it. But it is ethically wrong to try to get an activist Judge to impose his will on the CBA.
This is what the Union is trying to do; and is what these Judges that keep offering stays are doing. And they know it.