I would not give her any excuses for his violent behaviors.
IMHE she will run with it if given the chance. We all like to rationalize our faults, she is human and a Mother Bear (as are most of us
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If he did all that in one day, here, he would be suspended for 2-3 days depending on injuries so parents understand I mean business (also for myself and other parents to cool down). One more occurrence, terminated.
IMHO, One violent kid (in a group setting) can cost you your entire income and reputation. It is not worth the risk.