You got to fly a pretty shiney jet.. so of course its worth it!!!
MAybe a good warning to all the other peeps who sell their soul and grannys kidney to fly a jet without reading the actual contracts.
I agree, read the contract again, if the contract only says that you have to pay up in case YOU go, then don't pay anything. If the contract says that you have to pay in case they let you go it can only be for reasons of "gross misconduct"..
Otherwise tell them to sit on it and swivel..