You can remove the SIM card from a Tesla if you don't want it to phone home, and only connectivity functions are broken (obviously). This isn't a particularly satisfying solution, of course, but it's more recourse than I have against, say, Google shutting me down.

You probably actually have implied (or express) warranty protection against the manufacturer screwing with your car. Certainly for the first four years, possibly even after that. I feel like software updates ought to come with their own implied warranty, though that's far from standard understanding right now. Beyond that, it's likely that anyone deliberately degrading your car, even the manufacturer, is a tort.