I suppose. Though have you considered the fact that if someone has non-root local access to your machine, they are just one local privilege escalation away form

I suppose. Though have you considered the fact that if someone has non-root local access to your machine, they are just one local privilege escalation away form becoming root? And these things come out fairly frequently that you can pretty much count on one being found soon. In other words IMO you should either trust or not trust a piece of code to run on your machine. The distinction between root and non-root user running the code is more for maintainability and sanity and less for actual security.