I believe that type of arrestor would be used for things like Oxy/Fuel torches, natural gas lines, etc. Gasoline, being liquid, is a very different animal. I'm not even sure that flashback is possible if the fuel line is 100% filled with fuel (ie, no oxygen for combustion).
Flashback would occur if the nozzle got blocked, the hose got a leak, or, worst case scenario, I kept squeezing the trigger when the gasoline stream became atomized (becuase its almost out of gasoline). For the latter situation, a giant explosion is almost certain, in my mind. Atomized gasoline, under high pressure with a large supply of oxygen? It'd be like being inside an engine cylinder, only much more devastating.
Truth be told, this thing is terrifying to operate. But its so much fun!
I think that if I can keep the fuel from atomizing (by releasing the trigger before it starts to), I won't have a problem of sudden rapid expansion of my personal self.
The only solution that I've been able to come up with would be installing some kind of float valve inside the tank that would safely shut off flow somehow when the fuel level dropped below a certain level (like the overfill device in propane tanks, or your toilet).
Another solution would be to use a nonflammable gas, like nitrogen or carbon dioxide, to pressurize the fuel tank, rather than regular shop air. I like this idea much better, but, as with everything I do, price was more of an issue than safety. I wonder how much it costs to rent/fill an N2 cylinder from Airgas.