It is? They never defined militia because it was understood; perhaps the same thing with NBC? Why define what you know...
At best, it's a guess.
No, Congress attempted to modify the meaning of the Natural Born Citizen clause in 1790. That's a no no. The meaning is what it was in 1787 as it still is now when the Constitution was drafted and adopted by the Constitutional members.
At best, it's a guess.
It is best one out there based on facts.