Well, this looks like the opportunity for a teaching moment, not for the "victim", as he already seems to have his agenda in place, but perhaps for some of the folks here who may not fully grasp what might have happened when one tank is still showing fuel yet the engine won't run.
As described, (and most likely due to flying uncoordinated like the second image below, although other causes like a venting issue are possible) a pilot may end up in a situation where he/she has landed at an airport without fuel service available.
Said pilot opens the fuel caps, can measure a small amount of fuel in one tank, and zero in the other tank. Note that some of that precious fuel he/she did measure is below the fuel pickup and is unusable as well.
Now imagine what happens if a particularly bold pilot calculated that he/she theoretically had enough fuel to fly, perhaps, another 6 minutes regardless of reserve requirements.
Further suppose that a particular pilot does not understand (or care about) the fancy footwork required to keep the ball centered, and happens to fly in a somewhat uncoordinated manner - unfortunately keeping the tank with fuel just a bit lower than the empty tank.
It would then not be too hard to visualize a situation where all of the remaining fuel may become unusable, below the level of the pickup tube, due to that gravity thingy a poster mentioned earlier.
This is an example of unporting, or filling the fuel system with air instead of 100LL.
This is also why it is so important to understand the mechanics of the systems in your plane, as well as not violating regs like minimum fuel!
Even a flashy piece of glass in the panel denoting the exact amount of fuel left in the tank would not have helped this pilot out here.