Congress can make the whole world NBC. That is your position. It is a ludicrous position to take, but you own it.
It is not as ludicrous position as you postulate. The wisdom of the founding fathers is that the ultimate redress for any grievous overstep of or by Congress, lies with the People. As Congress represents the People, if such and overstep occurs, it can be corrected by correcting Congress during the next election.
The same Article I Section 8 (even same sentence) empowers Congress to set a uniform rule of bankruptcies. In similar hyperbolic case, Congress could enable any business throughout the world to file for bankruptcy in US Courts. There would be many dire consequences to such a move that dont need to be discussed here for the purposes of this argument. None the less, the authority is clearly articulated at the feet of Congress.
I am of the opinion that while Congress is authorized by the Constitution, the restraint exercised is done so for either fear of being removed from their position by the People or those representatives that are honestly holding to principles. I would point out that in one overstep, Congress removed jus soli as a means of justification for citizenship. The 14th amendment restored that justification for US citizenship and made it difficult for future sessions of Congress to remove that justification. It was the People through the later actions of Congress via the 14th amendment, that corrected that overstep.
I am also of the opinion that should a Congress pass an Act that authorizes the whole world as NBC, the People would rise up, throw the bums out, and like the 14th amendment, correct the actions of Congress either via subsequent Acts and possibly via another amendment.