He tried to kill a child to protect his family.
He killed Alton/Cleos (when he could've faked his death) to escape against 20,000 men.
Also being a kinslayer is probably even worse than being a kingslayer in Westeros.
There's more justification in killing the mad king than there is for what happened to Bran and Alton. I'm not sure why you think trying to kill a small child is justified for any reason.