Did the crew have a paper flight log, or was it all done via computer ? If it's all computerised, surely there must be some method of checking gross errors on fuel. If you go overhead point "A" with enough fuel, point "B" with a little less than you need, and point "C" with a lot less than you need, don't mental alarm bells start going off ? Presumably before the thing became a glider, there were fuel low level alerts. How much fuel remaining once they are displayed ?
As regards the F.O., I would hope that anyone I fly with would firstly stop me from getting even close to this position, and secondly, if I was "commanding" enough to force the issue, would take control. Not an easy decision I know, but better than being flown into a hole.