No, it was combative, regardless how true and factual. True and factual != polite and neutral. (Do you let every overweight person you see, know that they are fat? It's true and factual, so if they take issue with it, it's because they have a problem!?).
In fact, your response to the parent was fairly combative as well. Instead of pointing out a problem in the parents point you have instead tried to find fault in the parents character.
In fact, your response to the parent was fairly combative as well. Instead of pointing out a problem in the parents point you have instead tried to find fault in the parents character.