Maybe it's not quite theft, but like I said, at minimum, I'd expect Tesla to refuse warranty repairs (hack the software to open Plaid mode, lose your drivetrain coverage, etc).
Trying to think about it in terms of "normal" cars - unlocking Plaid is similar to reprogramming the ECU on an ICE to deliver more power.
I don't have any trouble with plaid - it is hardware/software with 3 motors and other hardware, plus control software.
There is also law in place to refute what you said. Manufacturers can not deny warranty coverage if you jailbreak your phone or hot rod your car, and this is similar. (I believe they have the burden of proof if it seems you did the damage)
Yes, I mentioned that law above. It doesn’t protect consumer who modify their cars beyond original spec…
If the manufacturer can show the change contributed to the failure, they can deny coverage. Vastly increasing the power output of the drivetrain would likely cause a voided warranty on the drivetrain.
Unlocking heated seats wouldn’t void the warranty on the drivetrain, but could void it on the seats and related electronics.
Trying to think about it in terms of "normal" cars - unlocking Plaid is similar to reprogramming the ECU on an ICE to deliver more power.