it's the same premise as stand your ground

In the same way that the above simply leads to more people killing each other. Giving 13 year olds the responsibility on whether or not they should resort to violence just leads to more unnecessary violence. Zero tolerance reduces fighting in school and removes any accusations of racism, favoritism, bias, etc. No need to play judge and jury, etc. Everyone just goes home and gets time to chill out. If you have a bully and want to fight them that bad, take it off school grounds, or eat the suspension. Most students will recognize that it's not worth it and learn self control or how to handle a stressful situation nonviolently