The right to self defense does not confer the absolute outcome of successful self defense. Take for example the American Indians many of them where well armed and lead self defense campaigns, some successful. Though ultimately unsuccessful in the big picture, it did have a limiting factor on the atrocity of American Indian genocide. Contrast that with the German Jews who did suffer a slow roll of disarmament, and you get wholesale extermination. The Indian gun brought the US to the negotiating table where in Germany there was only a final solution. Make no mistake Sherman was just as hell bent as Hitler on total eradication (Sherman is credited with originating the term Final Solution). The difference is the gun stood in the way of Sherman's goals.

If we are specifically talking about the recent issues with Black America that is a different debate all together as their are cultural implications that go along with it as well. One could blame institutional racism and I am sure it plays a factor but simple narratives are rarely the whole picture. Many of those shot have embraced a faction of US black culture that is fatalistic and backwards at best, therefore it is hard for them to gain broader sympathy beyond their own group who tend to see the world thru black perspective. That being said, they still have the right to self determination and self defense, if they truly are being oppressed then they should take up arms and fight that oppression. But they will have a hard time gaining broad support if the action carries the banner of an individual like Michael Brown, who had just robbed a store and was charging the officer.

There are systemic problems in the black community such as the individuals who told the truth about Brown's shooting at the grand jury now being targeted by criminal groups that act as thugs for powers in the black community. The point being is, the dynamics of a handful of killings of blacks by the government does not constitute genocide and the circumstances of many of the cases would be hard pressed to garner broad support outside of their community. The black perspective is that this is racism and it could be, but I don't personally believe that racism paints the whole picture. Regardless of that fact, the black killings and American Indian genocide are completely different examples where one is clearly self defense while the others have questionable criminal activity and police actions associated with them and where further reviewed by independent committees such as Grand Juries.

A constant is that bad men are always willing the use force and will go to any length to gain power of force. Another constant is that bad men are not going away. If this flame thrower was some how the end all be all, you can bet whether legal or not, the bad will get it, build it, do what they have to do to acquire that power. Ignoring reality by trying to ban items only furthers the problem because a man hell bent on power is going to, via whatever means possible, gain that power and the balancing factor has been removed. An example of this was the LA shoot out, where an entire force of cops what outgunned because policy up until that point prohibited regular police organizations from carrying military style weapons.

Is there a practical civilian application for this device, who knows? I personally doubt it, other than a really cool camp fire lighter, but that is not the point. The point is severely punishing wrongdoers does far more to prevent evil than parenting grown ups. For some reason as a society we have trended more towards the latter and gotten far more soft on the former. Yet a guy in France where civilian guns are all but outlawed, shows up with another AK but we somehow think banning this thing will make it go away.