I usually hesitate to respond to topics like these because, there for the love of god, go I, but...
Come on, basic airmanship!!! The wheels hang out, sure, I admit, I would try and see if I could make it too. As a matter of fact, I have been in a similar situation once ( granted in a turboprop) and I did continue to the destination.
However, FMS aside, and knowledge about fuel predictions, etc, etc, you have an operational flightplan. In a situation like that you compare the OFP remaining fuel against the actual fuel on board. You get the picture, at each waypoint the actual remaining fuel on board falls more and more below the required fuel on board as per OFP.
Personally, I tend to trust the OFP ( we use LIDO) more than the FMS as the FMS uses average inputs while LIDO looks ahead. In any case a combination of the two would yield the best info to decide to continue or not.
In this case, I feel the guys really f%&*k up.