Doesn't matter if REX fails to uphold their end of the contract, that is a stand-alone issue and it does not void the obligations of the other party.
As for QLink bonding, it says on their website "full cost of the Type Rating"
How much is that? I've asked them, but I never received an actual figure??
FSI charge about $34k for a DHC-8 type rating, if QLink is anything like that, I think it's a bit steep.