The odds are someone blowing themselves up on a plane will be male, that is true, it is where the numbers point. But the use of women (and the elderly, and children) to smuggle weapons and explosives goes back decades (probably centuries). One of my roles as a woman attached to an all male army unit was to conduct searches of civilian women, as they were used to smuggle guns and things used to make explosive devices, because they were rarely stopped by security patrols (given, in part, that at the time most patrols were all-male and thus couldn't search women). Sometimes the women were entirely complicit, other times they were under duress, forced to do it by husbands and brothers.

The second airport security are told to think women / old people / children as zero risk is the second those airports become less safe.

To add, Israel already had a pretty accurate profile of who they considered a risk - male, muslim, arab - in today's world, especially in a country like Canada or the US where there are many potential threat vectors, you cannot work on such narrow assumptions - or you will miss things.