Maybe. Are you important enough to get administrative attention after you're gone, or does your HR department only care as much as they have to complete their offboarding checklist?

People may talk, but the reality is that nobody is listening.

Companies are not sending private detectives, to follow engineers to their new job, and finding out specifically what they are working on, and if the contract is enforceable or not.

Mostly, people just forget about you, once you leave. People get away with lying all the time.