So, right now if there was a crazed nutcase killer in a building with a gun, students could head for their car, get their weapon and try to take the guy out. In that case, what would happen if the student who got gun out of car, went inside and killed the perp? Student just broke the rule and brought the gun inside. He should get a medal for breaking the rule and saving lives.
If the student carries concealed, then the time from visibility of the student's weapon to stopping an attacker might be five to ten seconds. If the student has to race to a car and return to the scene of the attack ( a questionable judgement call) it might be two minutes or more of visibility of the student's weapon.
The chances of the helpful student being mistaken for an unlawful attacker probably increases in proportion to the amount of time one is visibly armed. Having to run to the car and back might increase the chances of the student being killed by responding law enforcement by a factor of ten or more.
Concealed carry is much better than "car carry". And if law enforcement takes ten minutes to arrive, either is much better than "no carry".