Almost all good Senseis are going to (repeatedly and frequently) stress that martial arts are not to be abused.
Many parents find themselves concerned at some point whether or not their child will use their Judo skills for self-defense, or merely to hurt others.  This is a serious and legitimate concern.  While I can’t speak for every Dojo in the world, many Judo Senseis emphasize how serious it is to ONLY use Judo for the right reasons.  If a child is found to be using Judo to intimidate or bully other children, it’s not a stretch to say they can be disciplined or even kicked out of a Dojo for the wrong type of behavior.  This is largely true for a majority of martial arts, not just Judo.  Almost all good Senseis are going to (repeatedly and frequently) stress that martial arts are not to be abused.  We teach these skills for many reasons, but hurting, intimidating, or bullying other children are not on that list.  And again, a child may be expelled from a Dojo for improper or bad behavior.