This is the reason. One of my mentors was part of this effort; the Canadians were riddled with Soviet agents.

EDIT: downvoted for facts. Here's a reference:

But until then his assignment was to become Soboloff so convincingly that nobody would ever suspect he was a Soviet spy. Eventually, he was given responsibility for managing five recruited agents, including a Communist Party of Canada member from Toronto who worked for the company developing the Avro Arrow and provided its engineering schematics to the KGB.

https://nationalpost.com/news/canada/the-spy-named-gideon-bo...