Fuel Exhaustion Flameout Realism

Has the realism of the sequence of events and hands off flying after a Fuel Exhaustion flameout on the PMDG 777 even been discussed? Here is what I've seen:

 I noticed  that if I simply let the fuel run out and don’t touch a thing (previously I was setting a VertSpd descent rate at engine fail), first the engines fail with 300 lbs of fuel left, the autopilot holds altitude (I was at over 30K feet at Mach = .85) and lets the speed bleed off until it gets to 170 knots or so and then the stall warning goes off and the autopilot disconnects. Then the nose lowers under FlyByWire control and the aircraft descends at about 2000 fpm so the airspeed stays at 180 knots or so all the way to the surface. Either the system is running on batteries, the APU (which would autostart with a little fuel in its tank), or the RamAirTurbine prop comes out – just to keep the FBW alive.