I try to simplify my examples, but basicaly you must check the Muhammads... plus some random obviously NON-Muhammads as a deterrent - it is not so easy for the Islamic "Peace Corp" to find a white blond Adolf that will try to make connection with his 72 virgins in an airplane (that is the main reason for the existance of TSA - not to prevent Adolf from killing a passenger because he disagreed with the winner of the Eurovision music contest...)
Never underestimate the power of a few million dollars (or other pressure that's brought to bear) to break a profile that's so easy to spot. That's beyond the fact that there are plenty of blond blue-eyed muslims out there to break your profile on its own. Even Malcolm X attested to that.
When you have limited human and/or other resources you don't check a white woman's child just because... you know why (!)... you check Muhammad (plus his wife, and their children).
When you're a terrorist and you see the TSA feeling up Muhammad and his wife and children because of how they look, you naturally find a Robert who won't be searched because he doesn't look like Muhammad or his family.
What then? You'll start feeling up Muhammad and Robert and their families? What about David?
What about Elias who belongs to a completely different group and has a completely different mission than destroying a plane or building? Say he just wants to assassinate a specific passenger.
Just the Doctor
"There is nothing new under the sun, but there are lots of old things we don't know yet." -Ambrose Bierce