This is a total over reaction, and much like the security checking at airports that sees 80 year olds being wanded for explosives, is not sensible risk profiling.
Nothing on the day will stop a determined individual, even with a flight attendant in the cockpit.
The profiling needs to start before anyone goes near an aircraft, so the risk mitigation is addressed much much earlier.
9/11 cockpit doors have sure minimised terrorist incursions into the flight deck, but they do nothing if the problem lies in one of the pilot seats.
Maybe the locking technology needs to be revisited.