By all accounts, the Demers family collection is one of a kind in the world. I really can't understand why they would need to concoct false (and easily verifiable) stories about the vehicles, thereby undermining their credibility.
Whether or not these cars were used in films or driven by celebrities, they do deserve to be exhibited in a special place.
Certain people might argue that Ottawa is not a "car town" - that a car museum would be better suited to cities like Windsor. This however would not be a museum of the car industry in Canada. Rather, it is a private collection of vehicles from all over the world. It is a Canadian collection - assembled by a Canadian family and stored in Canada. (Isn't that what NCC is looking for?)
I for one would visit. I would take friends from out of town to visit. It would be a unique and fascinating addition to this city. If the building were large enough, it could also hold traveling car related exhibits or perhaps some of the Science and Tech collection.
After reading up on this collection, I would say yes to the car museum. But the family needs to stop making ridiculous claims if they cannot be backed up.
Here is the official website.
http://www.collectionautodemers.com/#!home/ceis