I agree, though I'm of the opinion that Rupert's land wouldn't be sold off until the mid-19th Century to either Quebec or to the US (or even to an alternate dominion that GB
might establish in the Fraser, Columbia and Mackenzie River watersheds -OTL names used).
Actually, Franklin was negotiating for what we know as southern Ontario and doing so at the expense of Michigan's Upper Peninsula, Northern Wisconsin and the Arrowhead Region of Minnesota as he thought the source of the Mississippi River to be further south than it actually is. (please forgive my anachronistic line along Maine's border):
In hindsight, that's the crazy part.