I was under the impression that engine TBOs were manufacturer recommendations rather than mandatory airworthiness limitations (i.e. an engine at 2000hrs turns into a pumpkin and falls out of the sky).
What about the insurance companies, you say? Well, I wonder how many life insurances have not been paid out because the bloke didn't follow the doc's recommendation to have a prostate exam or ECG or lose weight or exercise more and kicked the bucket soon after.