Interesting post. Boats compliant with US SAE J1171, free from fuel leaks, and using the bilge blower prior to starting should be safe. I'm not seeing how refueling a dead engine boat could result in a gas fume touch off. Gas fumes need a spark or cigarette, etc to explode. Liquid gasoline is fairly stable. I remember a 9th grade demo where a fireman quenched a match in a container of gasoline. It's the fumes. I'm guessing weird climate conditions allowed tank vent fumes to enter the boat and a spark source (radio, speakers, cigarette, static) touched them off.
But now I'm paranoid. Use dock cans for most of my gas. But when I fuel at a gas dock I'll give the blower a few more minuets before I start up. OK, I'll also turn on the blower during refueling.