If I understood it correctly what killed him was part of the ecig ending up in his brain. I suppose some are shaped a bit like a gun/cannon and if the battery suddenly explodes inside a metal pipe, the mouthpiece area might shoot out like a bullet?
It then caused a fire, but I suppose he was dead by then and the reason for the severe burn was that he was already dead and couldn't put out the fire. This got to be really rare though, but they should have this in mind when designing the units I suppose. Phones should really be less dangerous (assuming you keep it out of your mouth) but perhaps they too should be careful not to confine the battery to much.