Non-disclosure is just a form of contract. It doesn't itself protect ideas from theft. If they are valuable enough, or if the contract is not enforceable, then the person can still walk away with the material. They need to look to tradesecret law, that is IF any of their code qualifies for tradesecret protection.

The big if is in the relevant code: "(d) Trade secret means information, including a formula, pattern, compilation, program, device, method, technique, or process, that (2) Is the subject of efforts that are reasonable under the circumstances to maintain its secrecy."

http://www.leginfo.ca.gov/cgi-bin/displaycode?file=3426-3426...