Be sure to mention that risk when pitching your view of the NBC clause to voters and to their electors. And, don't you understate the likelihood of that risk when you tell them! ;-)
My point is, they CAN'T draft "natural born citizens." They have no claim on them. If the Canadians have a claim on them, they aren't natural citizens.
A man that can be compelled by foreign law to fight against his country is not a citizen who is free from foreign influence.