The problem is that who an "abuser" is is extremely subjective. In this case it's evil men. What if people buy these because they're scared of evil immigrants? The argument is the exact same.

And nothing is stopping abusers from getting these too. You think they have a little checkbox on the order you have to cross on the form so they don't accidentally sell them to the wrong person?

And who are they against exactly, gropers, rapists, people that hit on you in a club, any stranger that approaches you? Burning someone alive is a pretty big commitment, you better make sure you got the right person, or else you're just another psychopath with a weapon waiting for a chance to use it on anyone you dislike.