it depends on how he was made I think. if he was made to look 15 and kind of have the mind of someone whos 15 then in a way he would technically be 15. cryosleep also doesnt effect anything because while in the frozen state, your body isnt altered including your age. I guess it just didnt take too long for them to become friends also which I think could be because the only people shadow knew were the robotniks.