So the argument 'for' the new rule is that it prevents having an unknown person in the cockpit who has been vouchsafed by the other crew member. This includes those with ID passes such as off duty crew, ATC etc
Meanwhile one still flies with an often unknown 'other crew member'.
Lets see. A If I wanted to take over an airliner would I arrange to be guest/deadhead on the flight deck where I would have all flight crew to incapacitate (one would expect, unless some one suddenly rallied to the cause...), or would I wait until I was next on duty, get out of my - legitimate - seat to have a p!ss then clobber the other guy with the axe. Or the tech log. Or the Jep. manual. Or my nav bag. Garrotte with my shoe lace? etc etc etc.
Again, if I were a cabin crew member would I try to incapacitate each of the flight crew while in the jump seat, or would I just wait until I was next on duty & serve them 'Coffee with one lump or two (of strychnine)?'
If I were an ATC bod. intent on mischief would I try for a jumpseat & the joyous prospect of overpowering 2 flight crew or just crowd 20 a/c into the same 80 cubic metres of airspace?
If I'm ground staff would I try for a jump seat famil. ride or just wait until I'm next on duty & leave a little ticking present in some part of the a/c to which I have access. After I get the captain's signature on the load sheet, of course. Or hold up the last of the gear pins. Or whatever.
What next? A security barrier between each & every crew member?
Stupid rules are just that.