The purpose of the 12 months thereafter (as I see it) is to ensure that the contractor will continue to support patent activities that they participated in during employment.
If they conceived the idea during the term of the contract and the company pursued a patent, they are committing to continue supporting the company's efforts even if they leave before the patent is granted. It costs a lot of money to patent an idea and that would go to waste if the inventor did not provide that assistance.
For any other purpose, I doubt the scenario you presented would be enforceable, particularly in California.
[edit] FWIW, I would have stricken the wording that implied the company owned any new ideas post-employment if the engineer said it was a concern to them. I do want them to support the patent activities, but once I stop paying them, their ideas belong to whoever they sign up to next, if anyone. None of them so far have taken issue with the 12 months.
If they conceived the idea during the term of the contract and the company pursued a patent, they are committing to continue supporting the company's efforts even if they leave before the patent is granted. It costs a lot of money to patent an idea and that would go to waste if the inventor did not provide that assistance.
For any other purpose, I doubt the scenario you presented would be enforceable, particularly in California.
[edit] FWIW, I would have stricken the wording that implied the company owned any new ideas post-employment if the engineer said it was a concern to them. I do want them to support the patent activities, but once I stop paying them, their ideas belong to whoever they sign up to next, if anyone. None of them so far have taken issue with the 12 months.