Ah, that's much clearer...thank your for rewording your point. And yeah, that's a bit screwy.
I think--and this is without reading the relevant rulings, so take it as a wild-ass guess--that while regulating the rifles is one thing, outright banning an entire class of weapon fails to make sense. That'd be my guess.
The point about assault rifles is that it's deranged that the Supreme court sees fit to allow states to ban what are essentially light weight rifles with various doodads and decorations. Weird considering riffles of all types aren't much of a public hazard. Then turns around and rules that states can't ban handguns. Despite which because they can be easily concealed and are often used for street crime are a public hazard. (Absolutely no question).