I know they need to do some extra paperwork for transborder flights, but by the rule of the policy, you'd even have to be onboard a Saab 340 or a CRJ more than half an hour before take-off (The really short hops like Detroit to London, ON etc).

My concern is that with minimum connect times being somewhere between 30 and 40 minutes, you can be routed on a 'legal itinerary' but potentially be off-loaded and it be your own fault. What are the rules in this case?