This is one of the factors that also made me very much want to make this film, apart from the fact that I loved it. If the boy hadn't been Jewish and the man hadn't been Muslim, it wouldn't have made any difference to the film. I don't think it's relevant, really.
Muslims who convert to Christianity are not protected. That carries capital punishment. He would be given the opportunity to repent, and the Sharia court would need to determine if he was really a Muslim in the first place, did he know what he was doing, and once all of that has been determined, there is capital punishment for that in Islam.