There IS an argument for searching flight crews- namely, that they could carry stuff airside and pass it to an accomplice for use on another flight.
Of course, this pales into insignificance next to the monumental folly (in the UK) of allowing Sikhs to carry Holy Kirpans airside(that's a dagger to you and me). The justification for this piece of nonsense is that Sikhs are harmless (apart from the well-known and vicious Sikh extremists, of course).
So now, due to this PC idiocy, Sikhs (and only Sikhs) can carry a deadly weapon about airside. Oh, how safe I feel! Maybe I can get permission to carry an AK47, as my religion demands it...
Getting back to the original point, I can kill everbody on the aircraft (and hundreds on the ground) with one hand. First I use it hit the other guy over the head with, then I push the thrust levers forward, than I push the control column all the way forward. Don't need nail clippers or anything.
The current security measures are nothing more than a joke (a bad joke if you happen to be flight crew).