Another thing to consider here.
The skin is the largest organ of the body. If it sustains about 30% burns or more, it's very likely to be fatal unless immediate medical attention is rendered.
That 30% or more burn damage will take place in just about the time it takes to say "HOLY C***!" when you see the flames first shoot up.
That's. It.
And, as I mentioned earlier, once a person has inhaled the fuel/air mixture, that's a straight shot to the lungs for the fire. That's a death sentence.
And that's the potential fate for every person in the area.
Not just the people behind the perp. ALL the people ALL around the perp.
Including yourself and potentially the attendant, the people sitting in your vehicle, etc.
You can't "point" gasoline like you can a gun firing a bullet. A bullet which, even if you miss, will eventually lose energy, probably hit an inanimate object, and possibly injure someone in a very small chance (hopefully), all of which you have SOME control over; gasoline doesn't work that way at all.
It burns until the fuel is gone. If it burns the wrong things, it generates MORE fuel until IT'S gone, too.
It burns and burns and burns until it burns itself out or is contained enough to be extinguished.
If the wind blows, it burns hotter... and may easily spread.
If it rains, it may spread like a grease fire.
AND LET'S SAY THE PERP GETS DOUSED IN GAS AND CATCHES FIRE and nobody else is hurt or killed, no major property damage results.
Know what ELSE you can't do in this case?
You can't stop applying deadly force if the perp flees or stops his attack, that's what.
If you use a knife, firearm, club, etc. to wield deadly force and the perp ceases his attack and/or runs away, that's it... you are no longer justified in continuing to use deadly force and the instant you cease your defensive actions, you're done applying deadly force.
Not so with someone you've doused with something you can't promptly extinguish once ignited. (And this doesn't have to be something flammable...a caustic substance will fit the bill, too.)
I'm a huge fan of weapons of opportunity. And yes, I've considered this scenario, too.
But while everybody just loooooves to say things like "better judged by 12 than carried by 6", the plain fact of the matter is that EVEN SO, OUR ACTIONS HAVE CONSEQUENCES IN THE REAL, LEGAL WORLD. Those consequences could still gain oneself anything from "not guilty" to "death penalty", depending on how the government pursues charges.
And that's just the criminal court side. The civil side is wicked, too.
As we've all discussed here, there are many ways and opportunities each of us could use to mitigate the dangers, as well as apply other defensive tools.
So the takeaway here isn't too continue to seek ways of justifying the use of a form of deadly force which has serious potential hazards and consequences... it's to figure out other, better ways to prevent/survive such an encounter without potentially razing an entire city block.