Quelle horreur! Flamethrowers? Actually, most people believe that it would be perfectly legal.
It's a high-tech looking gizmo, but Musk wants $600 for his model. I don't think it would be good for home defense, but it would make get-off-my-lawn statement. Of course, for that, you could just buy a propane torch for a whole lot less money.
But, hey! If Musk wants to sell flamethrowers, I'm okay with it.