So my semiautomatic hunting rifle COULD have a grenade launcher as long as it didn't have any of the rest?

The M-79 grenade launcher was/is a single-shot weapon capable of firing 40mm flare, HE, flechette, and other rounds. But it's not, by these definitions, an assault weapon. But an M-1 rifle, which has bayonet lugs, can also be used to fire rifle grenades and so it would be?

I think they need something more to define "assault weapon" than the outward appearance.