I read in a linked article embedded in a thread on this forum that said his mother "took an oath of allegiance" to Canada before his birth. I wish I had saved what appeared to be a moderately credible source link.
I will look for it for a few mins then give up:)
But if she and dad both applied for Canadian citizenship and signed/swore an oath before he was born...I don't see how she could have conveyed Natural Born Citizenship under any reasonable definition. She definitely would not have been "subject to the jurisdiction thereof".
Key word IF . no reputable source say like the Canadian gov’t.. has said she became a Canadian subject.