The best argument to end the tax and harassment for suppressors is that they are literally gun mufflers. If excessive noise is bad from cars or tools or music and needs to be lowered to create a safe work environment, then is needs to be reduced for firearms as well. It is far past time to end this bullshit law.
The ATF would be the first government organization to argue, more noise is better and that having excessive noise is a public safety issue. This would lead the way to tuners and aftermarket car parts companies demanding to increase exhaust noise for public safety.