I agree that there needs to be some sort of assurance to PSA that the pilots hired will stay. Having said that, I think it's a mark of unprofessionalism to jump ship like that. If you elect to take a position at any company, you accept the benefits and the baggage that comes with it. Regardless of who offers better, you showed up for class. Simple as that. It's your responsibility to stick it out for a reasonable amount of time.