He’s also getting away with it because it was a propane torch mounted in an airsoft gun, not a dangerous weapon. It’s a tool in a toy, so basically... who cares?
Also, actual flamethrowers are commercially available and completely unregulated in 48 states: https://throwflame.com
Oh my god, I didn’t know that and to be honest, I’m surprised. My first reaction was that must be a satirical site, but no it’s a real and claims of legality are accurate.