Heck, completely forgot that. Never had it selected. Thanks for the hint.
However, this requires user interaction, the OS won’t set itself to autoupdate (At least I hope so).
If the installer is supposed to ask for permission, but due to a bug does not
Well, if the installer doesn’t ask, then the OS will ask — before being modified. That’s how it should be.
There’s also someting like “System Integrity Protection”, by Apple, a mechanism with the purpose of demanding elevated access privileges to do certain things. Not sure if it applies (or should apply) in that case.
And I’m not very familiar with how it works.