So, I'm now reading the article he cites to support this.
It's an old article, from 2013. It states that:
"Police statistics show 25 children of the 46,718 reported missing in 2011 listed as "abducted by stranger."
And then goes on to show that in the majority of cases that the abductor was known to the parents.
So, the useful dataset would be.
* How many of the children were abducted with unsupervised?
* In the Canadian population how many children in total are left unsupervised regularly.
From that we could calculate:
Percentage of children left unsupervised regularly who are abducted.
Percentage of children not left unsupervised regularly who are abducted.
Of course, correlation != causation. But if there is no difference between the two populations then that would tell us something. However, there isn't enough data in the article to make this assertion.