The same way referring to a semi-automatic rifle with a detachable magazine and two offending cosmetic features as an assault rifle does
You fell into the trap there. What you describe is legally (in some states) and WAS legally in Federal law an "Assault Weapon", not an "assault rifle" even if it is a rifle being described.
The similarity between the terms is deliberate, and was chosen by the antis for just that reason.
Assault Rifle had a commonly accepted definition in the firearms community long before it became a political football. And, under US law, assault rifles are machine guns.
When nutjobs were shooting up schools or workplaces (and then killing themselves) in the late 80s and early 90s, the press screamed "He used an assault rifle!" We answered back, "No, he didn't. It was just a semiautomatic rifle". Then the press screamed "He used a semiautomatic assault rifle!"
This proved to be too cumbersome a sound byte, and it soon became "Assault Weapon" (referring ONLY to semi autos with certain listed cosmetic features), no matter if they were rifles, handguns, or shotguns.
Call it a silencer, I'm ok with that, like I'm ok with Kleenex, Jello or other brand names that have become generic terms. And that is how it is named in law.
Call it a suppressor, because that is what it actually does.
but don't bother me with arguments over which one is "right", as dependent on your point of view (or maybe context) they both are.