Helmet fire, That all sounds very sensible and plausible.
My understanding is that the main tank has a ledge over the top of the supply tanks, and so while the fuel level is above the pump supply pipe entry into the supply tanks, they will be kept full by gravity until the main tank level drops below. Then you have two full supply tanks worth of fuel accessible, so the Glasgow aircraft sounds a bit more generous for unpumped fuel than the US accident you note. But it would certainly account for the events, and for pressing on with that cognitive gotcha.
The pumps left on, or operating automatically would have prevented it?
I really see no advantage to the pilot having to manage those main tank pumps in flight. Lights can come on to indicate they're drawing vapor and turned off or that they've failed. I can see the advantage of having to make a conscious switch to a reserve tank at a set time in a simpler system, but not here.
If the capacitive (and warm wire) fuel meters are prone to organic goo (and nothing says they were here), would silver coated pressure sensors at the bottom of the tanks, or ultrasonic column sounders work better? Not that it seems to be a problem with the generation of the warnings, but perhaps their display and appreciation.