My thought is why was your son punished when he was protecting the other kids. He was responding to the issue, in defense of the other kids.
YouTube has an app for younger viewers;
YouTube Kids is designed to "make it safer and simpler for kids to explore the world through online video – from their favorite shows and music to learning how to build a model volcano (or make slime ;-), and everything in between. There’s also a whole suite of parental controls, so you can tailor the experience to your family’s needs." My 11 y.o. daughter watches it a lot and hasn't seen anything offensive. There is a version for both iOS and Android.