The story even after a search said nothing about intent. It said the knife was locked in his own vehicle.
So far your argument amounts to: well it could have been this way. I am stating fact based on what was reported not speculation that is irrelevant.
Man is drunk and accidentally walks into the wrong house (happens quite a bit) and is charged with criminal trespass, not burglary. Because no intent to commit a crime existed.
Accidents happen and the school should recognize this and act accordingly.
Zero tolerance is moronic at best. Let the punishment fit the crime.