There's also a buried reference to using a several-years-patched gpac bug to gain root access before this thing can do most of its stealth stuff.
Basically, it needs your system to already have a known, unpatched RCE bug before it can get a foothold, and if you've got one of those you have problems that go way beyond stealth crypto miners stealing electricity.
I have mixed feelings about the necessity of this.
On the one hand, I know they don't really need the cell phones, because they didn't exist when I was in school.
On the other hand, the kids who are paying attention to their cell phone rather than the teacher probably wouldn't listen to the teacher if the cell phone wasn't present, either, and some of them would be far more disruptive toward other students who are trying to listen.
On the third hand, expecting the kids to pay attention all the time even if they've already mastered the subject and are bored out of their skulls by the repetition needed for the kids below the class median to have a chance of understanding too is a problem in and of itself.
Fortunately, I am not a teacher, a student, or the parent of a student, so I have no horse in this race and am not required to make a decision on whether the bans are useful or just obnoxious.