Certain speech, for example, cannot be banned by the States except for reasons like inciting a riot as you've described earlier. For reasons relating to directly endagering others.
But I feel that it cannot be banned by the federal government for any reason, even directly endangering others, because teh federal authority on these matters has been removed by the BoR.
So regarding a state trying to implement an assualt weapons ban, I believe you explained the reasons they cannot perfectly before.
Simple possesion of a firearm of any sort cannot be construed as a clear and present danger. The states do not have the right to prevent simple possesion.Simple posession of an 'assault weapon' creates no such [clear and present danger to others -- an immediate threat to pubic safety] -- and so, the argument you present, above, falls to support the constitutionality of banning them.
They can, in essence, eliminate people deemed to be a "clear and present danger to others -- an immediate threat to pubic safety" from eligibility for firearms.
Thus the State's rights remain solely in the realm of preventing such clear and present dangers from being eligible for militia duty.
The federal government does not even retain these rights.
I believe that the States and local governments are the only entities that have the ability to make laws abridging these rights, and ONLY for reasons related to immediate threats to public safety. The federal governemtn reliquished this ability to the states with the BoR, but that doesn't mean the states have the right to arbitrarily infringe on the rights outlined by the BoR.