His mentally ill child was exploited by the Muslims of the Islamic State, who used him up, in their version of cannon-fodder, as a suicide bomber. It's what gave Jake Bilardi's life meaning -- because Jake Bilardi was a mentally ill Westerner. If you are a Muslim, you don't have to be mentally ill, in the ordinary sense, to become a suicide bomber. You need only take Islam even more to heart than you normally do.
How should a Western parent attempt to immunize his child or children against such things? Teach them the truth about Islam, this crazy cult, with its Qur'an, and its Hadith, and that exemplar Muhammad as "the Perfect Man." Teach them to be wary of Muslims, to recognize that Muslims are mental slaves to Allah. Do what you can, because if they are or seem to be perfectly healthy and stable, you never know. Prepare them now, when they are young, to resist Islam and to see through all the ways and wiles of its defenders. It will do them good. It will make them better citizens. And they will understand what is happening in the world, unlike so many of those who now presume to protect and instruct us, and do neither very well because they can't or won't allow themselves to grasp the full meaning and menace of Islam.