Yes, but the children were mostly killed not because they had actually done something, but because they had seen something they shouldn't have or because the murderers wanted to hurt their relatives through their deaths. It's not like they punished them for something they had actually done. So, in my opinion, this is dishonorable even according to medieval standards.
The male children are killed for fear that some day they'll be men and they'll want vengeance. But you're right, there's no honor is killing a child. Ever.
"I got news for you. If it wasn't for the toilet, there would be no books." --- George Costanza.
