It's a difficult question. I certainly don't claim to speak for Canadian law on the point.
As a matter of international law, the law punishes states and non-state actors who recruit underage children. If members of his family could be considered members of a non-state actor, such as al-Qaeda, and responsible for his illegal recruitment--and I know there are a lot of ifs in here--then they could be considered guilty of violating the optional protocol on the involvement of children in armed conflict. But it would require much more investigation and more facts than I have at my disposal.