Understand that bureaucrats in general, and school administrators specifically, make "zero-tolerance" rules to free themselves from making decisions. Of course, they are paid to make decisions based on their experience, but they don't want to. So, they make "zero-tolerance" rules so that all decisions are pre-made, and they can never be accused of making the wrong decisions. In short, they are cowards.
I thought they were a result of PC.
Student #1, who is black, brings in a loaded gun, points it at another student, and only misses killing him because another brave student grabbed at the gun before it fired.
Student #2, who is white, brings in a keychain with a 1/8-scale plastic Luger.
Since (according to Jesse Jackson et al.) the only explanation for a decision to punish student #1 but not student #2 would be the fact that the former is black, and since it's obviously necessary to punish the former student, consequently it's necessary to punish the latter student as well.