Earlier quoted context omitted.
Of course you can lock stuff via enterprise settings so that about:config entries can't be modified by local users, but that takes time to find out and test, while removing the weird non-Chrome browser that's still present mostly for inertia reasons but nowadays only gets used for evil porn is much easier.
Saving time by applying a non-solution 9like removing one browser instead of treating the root cause) is not actually saving anything. You just kick the problem further down the road. Firefox prefs are documented even if not in the most user friendly way [0][1][2][3]. For the most part performing some basic hardening and other useful config on the browser takes less than a day. A person with some IT background should…
this stuff about finding all the right config files during "basic hardening" and having it just work is the stuff of armchair commenters and people who do IT/security on a well funded, sufficiently redundant team. assuming the latter would be the people in charge of school IT is hopelessly naive.