Correct; unless of course he is apprehended and charge with Treason -- which is a capital crime.
I am not willing to go so far as calling him a traitor, but he certainly broke his oath (or contract, if you prefer).
The trick is always figuring out what the most moral course of action is between two immoral choices.
You always have to go back to the most basic principles of right and wrong and either look to natural rights (if you are "small 'l'" libertarian) or the good of the collective (if you are a progressive communist).
If he kept his secrets, just who or what would he be protecting?
If he tells his secrets, who is he protecting?