Extensive research shows that using harsh verbal discipline and physical hostility is counterproductive to good parenting. It increases the risk of delinquency, fighting, misbehavior and belligerence in teens.First of all, fighting and belligerence aren't always bad things. Sometimes they are exactly the proper and just response, in which case the son you have raised with a capacity for them will be the person with the capacity to act virtuously in those circumstances. The one you've raised to shrink from conflict and physicality will be unable to defend the right when push comes to shove.
But, second, this particular teen was already physically present for the purpose of joining a riot. I don't think you need to worry about 'increasing the risk' of misbehavior on this occasion. Mom was just trying to keep her son from getting himself killed, as was not improbable under the circumstances. Not only is the author a pansy who should mind his own business, then, he's also got his head entirely in the wrong game.