I understand what you are saying Wookie. And as I said I have similar inputs on my Bell receiver. And I know even though they look like regular composite yellow inputs that we've seen for 20 years, the ones on Bell wait until they sense a digital input, and then they allow you to select them as a source.
It could also be something that isn't activated on the Shaw boxes, but somebodt like Comcast or something does use them; and it's easier for Shaw just to use the same box.
Have you done a search on
www.digitalhome.ca/forum ? I would think you couldn't be the first one to have tried this.