It's sort of unclear from the article how the ECU was disabled. Was it damaged during the crash or did the insurance company disable it when they sold the car?
In any case, it seems to me he has some recourse against the seller of the vehicle. On the other hand, the laws should address this scenario. California law already strongly protects consumers from insurance forcing shops to use second-rate parts. If that is a good idea, and I think it is, we should have some requirement that also forces manufacturers to make replacement parts available under non-discriminatory terms to consumers, parts stores and anyone else who wants them.
It's not for Tesla to decide what car is roadworthy. This was a business decision and Tesla knows it. It has nothing to do with actual liability and more to do with their stock price every time a Tesla driver goes off the road and t-bones a minivan.