The only reason people don't know what to do with any potentially dangerous thing is when they are artificially prevented from exposure and learning the appropriate common sense the same way they have to for everything else in the world like nail clippers. You don't eat them and you don't cut your actual finger off, because somewhere along the way you played with one or if you are particularly dimwitted, someone showed you and you memorized a rule. The danger of a phone is no differrent than the danger of any other computer, or a toaster oven, or fucking breathing outside of a padded cell.
This line of argument is exceedingly offensive and should be ridiculed without a hint of mercy or acknowledgement.
You could for example make it so that phones could only be unlocked within a few days of the purchase (first boot) date, and put a scary warning on it. That'd put a stop to 99% of people being tricked into unlocking it.
You could also put a scary warning on boot that allowed anyone to tell it was rooted to stop people selling them while rooted.
The point of blocking rooted phones isn't "security", it's to maintain control of the user experience.
That came out creepier than I'd like, but idk how to rephrase it right now.