Lovely story, well-painted picture. Your POD seems convincing to me.
For all his bluster, Trudeau (will we soon have to specify we mean Pierre Elliot?) was probably the best man for the job of confronting the FLQ. When I read about his attitude to sovereigntism, I concluded he had to be from New Brunswick or a Franco-Ontarian (no Quebecker would address his compatriots that way, I thought). But the fact that he was from there, spoke the language etc kept people from conflating the pursuit of the FLQ with a crusade against the Quebecois.
He was a strange man in so many ways. His English sounded like a Francophone with perfect fluency - but his French sounded like an Anglophone with perfect fluency!
His dad was Franco (Trudeau), mom Anglo (Elliot), and he was equally at home in both worlds - but not perhaps completely accepted as 'one of us' by either.
A brilliant, brilliant man with enormous blindspots.
It is telling that when MacLeans ran polls a few years back on the Greatest Canadian ever and Worst Canadian ever, he made the top 10 in both lists.
His over-reaction to the FLQ crisis was a disaster - although, it's certainly true that overreactions by an Ango leader if he had been assassinated would have been worse.
As for Diefenbaker coming out of retirement and becoming PM again, ??? What? That's probably the most improbable part of your TL. IMO.
Nunavut returned to Canada? Say what? Nunavut is north of Manitoba, no way would Quebec have or claim it.
Did you mean Ungava, perhaps.
Or is Ungava 'East Nunavut"?