[miki123211]

I've said this dozens of times on here, but IMHO the correct solution to this problem is:

1. Allow the user to choose between developer control and owner control, but only at first setup / after a factory reset. This prevents somebody with physical access from easily and covertly installing a backdoor.

2. Have a scary screen on boot announcing that "your device has been hacked", bypassable via a secret combination that isn't displayed on the screen. This isn't a problem for anybody who roots the device themselves, but instantly gives the game away if a third-party messes with it.

[hoopla_ching]

I like this. The factory-reset gate stops the attack without locking owners out, and the boot warning is basically what Android does with unlocked bootloaders.