Because a flight engineer with a laptop could disable everything, system by system. He’d be ‘remote’ flying the craft from inside the cockpit.
I read, just recently ... that to turn off one of those systems would require someone crawling down through an access hole, and that they would be in plain view of the others on the crew (and passengers in First Class). So, apparently not everything can be shut down that way.
Furthermore, I haven’t read anywhere else where that navigation system is accessible through an outside computer to be able to change or enter a new waypoint.
Could you elaborate on those two things?
What makes you think that is possible?