Its the same kind of logic that says the 2nd Amendment does not include Assault Rifles.
If by assault rifles you mean fully automatic version of AK47s and M16s then I guess the court disagrees with you. If your reading of the intent of the first amendment means everyone can own full military weapons, then they could also own fully functioning tanks and artillery pieces. I can certainly understand that view, but I do think the court would agree.
On the other hand, if your view is that free speech must never be abridged, then how do you justify slander and libel laws?