
"Assault rifle" and "assault weapon" have real and distinct definitions as far as I'm aware. Assault rifle means a select fire, intermediate cartridge rifle, usually intended for military use (naming convention is based off the Nazi's Sturmgewehr) Assault weapon is literally every single gun that was restricted by the 1994 federal assault weapons ban. Both types should be legal, but neither is a made up term.
You do provide good evidence, however I do feel the term was made disingenuous on purpose over time. At the end of the day they’re both guns that do the same thing. One just lets you shoot a little faster. You can dive into aesthetic qualities but I would say those are irrelevant. A rifles is a rifle, a pistol is a pistol.