This is a completely different deal than not having it in the law in the first place, because now a private school potentially takes on some liability by creating exceptions. If it were not in the law, this would not be the case.
I'm not sure I follow/understand what you are trying to say.
Ex 1
Are you saying if there was no GFZ (ie. no law) and you carry at the school and get hurt/hurt someone that the school is not liable.
or
Are you saying if there was no GFZ (ie. no law) and you carry at the school and get hurt/hurt someone that the school is liable
vs
if the school makes an exception to the GFZ (ie. current law the school can exempt you) for you and you carry at the school and get hurt/hurt someone that the school is not liable.
or
if the school makes an exception to the GFZ (ie. current law the school can exempt you) for you and you carry at the school and get hurt/hurt someone that the school is liable.