Pretty tough chain of events, like they say when the holes line up you're in trouble.
Sounds like they needed to be a lot more careful with fuel drains, and rather shows the point of why a lot of aircraft have two fuel tanks. If this had been a PA-28 or similar they'd of had a whole load of extra fuel available.
The other thing it raises is accurate fuel gauges in GA aircraft. I'm sure most people don't trust the gauges, even if they are showing zero they will ignore them as they did a visual check of the fuel before they left and know the fuel burn.
Still don't really see how they both lost their lives, from the description sounded like a suitable landing site where a landing could have been made where perhaps they could have walked away with minor injuries, or possibly serious injury, but fatal injury is very unexpected in this circumstance.