Anyone under the age of 18 need permission to play KO in the TOS. It is his responibility to make sure he is happy for his child to play in the potenial risks a online game can bring. Because of this he does not have a leg to stand on in an counrty.
I would send the SS on a complain to customer support as he is harrasing you and accusing you of a serious action. Threat towards you and your account are breaking the TOS and you can get him banned for that.