CC in FD is not at all a tentpeg stopper; for instance:
Bad guys infiltrate a number of sleepers who wait, for years if necessary, for opportunity to bludgeon single pilot.
Why bother with CC and why wait all that time. Why not train a few people to fly (P2F) and get jobs with carriers. Then there will be lots of easy opportunities to take control and crash the aircraft when the other pilot leave the cockpit. Without a "two person rule", that so many professional flight crew seem so set against, what could be easier?