“So maybe the question should be, if Cruz returned to Canada in 2011, with his Canadian BC, could he be recognized as a Canadian citizen.”
Yes, but so what?
My father explored becoming an Irish citizen, and found out it was possible.
Melania Trump became a US citizen by becoming the green card / mail order bride of Donald Trump.
It is entirely possible to be eligible to be a citizen of multiple countries at the same time.
This is part of the brain damage of the eligibility activists.
You don’t understand what you are talking about.
Is Melania Trump eligible to go back to Slovenia and be a citizen of Slovenia?
YES!
Then it is simple, if Cruz could be a Canadian citizen because of his being born there, then he is not natural born in the USA. A natural born citizen of the USA can not become a citizen of another country without either renouncing his US birthright or pledging allegiance to that foreign country. You just proved what others are saying. Ted Cruz is not natural born.