It was a few years back when this was implemented, primary to stem title washing, namely due to flood damaged vehicles. Often cars would be written off after a storm and be 'imported' to ontario (directly or through a proxy province). Since the MTO runs their own show for vehicle history, it would look like a clean vehicle to an unsuspecting buyer. I get why they did it.
A 2014 SP should be able to use any frame from 08-16. The engines never really changed. Even the new 17+ motor uses the old block wtih a different head, although frame mounting may have changed in 17.
Where things become challenging will be the title for the frame, not the frame itself, as you are finding out. If you have a bit of time, hopefully you can find a clean canadian one. A US one will be more difficult, but likely possible. A US frame would need to be clear title and likely need to go through the standard export/import process, provincial and federal inspection, etc. It's not hard, but takes a bit of running around. I haven't tried just importing a frame, I usually do a whole bike, but I do know the resulting bike really needs to be stock if you go this route. You can ask the RIV about importing a frame only, but they are generally textbook only answers, which tend to be vauge and open to interpretation, also be careful what you say to them.
Normally for importing, you'd use a standard form 1 vehicle import. Do not declare it as 'parts' (form 3). Parts vehicles will result in a blacklisted VIN you can never register on the road. If you declare it as a standard form1 import vehicle, If must pass both federal (Canadian Tire only) and provincial (regular safety) inspection within 30 days. In particular watch the requirements for the federal inspection, i.e. the exhaust. it needs to be stock. The RIV says it must be returned to the US or destroyed (their words) if it does not pass.
