Well, almost everyone has agreed that SOME line must be drawn. Presumably, as a representative democracy, the one's to draw the line must be the government. They derive their power from us. Therefore, they are the ones with the line drawing power. (Assuming their is some protection within the 2nd Amendment for any line drawing.)
One of the problems with holding a person strictly liable for the damage caused by their superhazardous weapon is that it is a post facto fix. I could inadvertently launch my safely stored ICBM and the result could be the anihilation of an entire city AND the starting of an international war. Are you really willing to contend that the drafters had in mind the idea that any citizen had a constitutionally protected right to possess single instruments capable of unquestionably starting international mayhem? Obviously, they could not have conceived of a weapon as powerful as the nuclear weapon. But, if you are going to go with a textualist reading of the constitution, i.e. what did they mean at the time, the sole protection afforded would be that of the weapons known to them and afforded by them at the time. As soon as you are willing to make the jump to the second amendment applying to firearms that did not exist at the time, aren't you using the same sort of logic that proponents of the "living" constitution are, i.e. that the constitutional protections are different now because of changed circumstances? Also, wouldn't you then have to require registration of these kinds of weapons? If you didn't how would you know who it is you have to hold strictly liable?
You could try and make and argument that the "spirit" of the 2nd Amendment when it was drafted was meant as a means for the people to protect themselves from the tyranny of government, therefore, as the weapons of the government have advanced technologically so to should the scope of the 2nd Amendment. As such, citizens should always be able to have the same technological tools at our disposal as the government so that the tyranny can be adequately opposed. Is it possible that weapons as potent as nuclear weapons call for a tempering of this line of thought? I fear slippery slopes as much as anyone, but, as my initial question suggested, it seems like something along these lines has to be necessary. Otherwise, any jihadist, drug lord, CEO, or corporation could legally purchase and hold a single tool capable of crippling entire nations. Look at what the mere threat of nuclear weapons have led to in both Iraq and North Korea. The second half of the twentieth century was dedicated to careful avoidance of this sort of armed conflict. With nations holding these sorts of weapons, the likelihood of their usage is fairly law. Put them in the hands of anyone with the jack to afford them, and their becomes a clear international problem.
At some point, public policy trumps the bill of rights. You can't yell "Fire" in a crowded theater, you can't own or distribute child pornography, and there should almost certainly be a limit as to the extent of the 2nd Amendment.
As a brief aside, Senator Clinton being elected president would not de facto give her the authority, ability, or power to decide what the scope of the 2nd amendment is. The executive, though powerful, doesn't get to shape legislation specifically, and no one gets to enact (and see stand) unconstitutional legislation. That's party of the beauty of the three branch system that we have.