Zero tolerance is set by people like this guy in NY and school administrators, in many cases, are NOT ALLOWED to exercise judgement. I've seen it in action. Principle MUST enforce or face discipline his/herself. Personal experience with my kids. Principle literally faced the decision of her ass against my son. Son lost and was suspended for a day because he got hit. No retaliation. But he was "involved in a fight". Automatic. Had she been allowed judgement, my son would have gone to school the next day. (but this is fl...where zero tolerance has surpassed its own wildest dreams)
I don't see it justified as a slippery slope position. I see it justified as a position that eliminates favoritism (read limits accusation of racism/nepotism, etc). Johnny pointed and went bang...he got scolded..Tyrone pointed and went bang...he got suspended....why? (introduce lawyers, etc).
I know you oppose the ban...you cook...BUT its justification is EXACTLY THE SAME as was used for trans fat. It is one more step down the slope that started when they said you can't use this ingredient when cooking. Salt is just one more.