The point of a tribunal is to gain some form of compensation (be it monetary or by way of apology) for the upset caused from what appears to be an unfair decision by the company concerned.
It is also so that the company does not do such things again and can put in place procedures in case they find themselves in a similar position.
Yes, Ben has managed to get a job in Luxembourg but this has meant that he has had to move to spend more time looking for a job, interviewing etc, and then move to a new country in order to take the position. NATS acted unfairly, in a lot of peoples opinions, and Ben therefore has every right to demand some for of reccompence.