Not quite. Wads with an overblown sense of entitlement are 90% guilty. Cousin and friend represent 10% of the problem, and even then I'd give them a pass for not engaging further with the Neaderthal, thus avoiding a potentially escalating confrontation.
Adults shouldnt be held responsible for civilizing miscreants.
PS I would have reported the creep.
I'll agree with you on everything except the "held responsible" part. If nobody tries to fix the situation, then a bully will continue to bully. You sort of contradicted yourself. By reporting the "miscreant" you are taking responsibility for trying to civilize the "wad".