Violence was the wrong answer. But a swift and strong reaction to defend someone being bullied is something to praise. At a time when a large portion of society is actively trying to demote women to the position of being property instead of people with equal rights, that instinct is even more important to encourage.
So, while violence would normally be something that is met with swift punishment of its own to try to correct the child's behavior, in this case, the balance tips a bit the other way. In this case the kid was already ejected from the game and the parent decided that was enough of a punishment without needing to add additional punishment. Some people feel that there should also be some reward to encourage the instinctive feeling.
I have not seen any response so far that denies that ejection was not warranted as a punishment for the violence.
As a parent you have to be conscious of the lessons you teach your children. Harsh retaliation to anything that the kid does wrong will end up squashing their ability to act for themselves or stand up for themselves. In fact it may even lead to them becoming a bully.