Fifita does have a case to take them to court. Most players have clauses in their contracts to increase their salaries if selected in rep teams, so theirs the monetary loss. Couple that with clear correlation of a players earning potential increasing when selected in rep teams etc... And as per the Fair Work Act and Anti Discrimination Act he is being 'victimized' and 'discriminated' against (note there are players in the team selected with recent criminal convictions, far more serious than his). Pretty easy case for hi to win if he wants to go there...
But as someone else pointed out, he is a fckwit, so hopefully he doesnt get any $ out of this classic NRL f**k up...
The NRL would just say those players were punished and have met whatever criteria the NRL and their clubs set for them to be back playing. Fifitas issues are still current and are still being investigated or they could spin it as him not being selected is the punishment, either way it seems an easy accusation for the NRL to contest.