I'd normally be loathe to ban someone for something about character ages, and it might not even be untrue, but their attitude just doesn't seem good. Dismissiveness and passive-aggressiveness towards Twilight-OP, citing something they themselves wrote as their source, and doing so in a condescending "appeal to authority" kind of way, no less...
I'd say at least a moderate ban, mainly for the bad attitude and questionable citation behaviour. Strongly encourage them to change their ways, but their attitude leads me to think that might not happen. I wouldn't object to a long-term ban, to be honest.