As far as I know Hizb ut-Tahrir was banned in Germany because of antisemitism not because of terrorism So tell me, who is to decide what kind of world view should a pilot have? Will you apply the same standard with a pilot whose brother is a member of Arian Brotherhood?
At the end of the day it all comes to simple fact: was Jamaluddin member of a terrorist organization or was he plotting an attack? If you cant prove that and you still fire him, than pay up (I'm not sure how the tax payers will look at that).