Lib dem,
I think you are right but from what I understand Unite have given an undertaking NOT to pursue it throught the courts in this agreement and that is what the sacked or suspended crew are upset about because although they could persue it in the courts as you say, they cannot have the financial assistance of their union.
Which of course is the main reason a lot of crew join the union for.
Some of the sacked and many of those, that might be about to be sacked are of course union reps! Which is what is complicating and clouding the whole issue.