Having visited Toronto a lot I think it is an absolutely beautiful city and would be a great place to LAN in terms of things to do outside of game, nice city/not a ton of crime, places to eat, afterparty spots, etc. as well as the relative closeness to east coast gamers and the decent population of TF2 players in Ontario.
The main issue however is that the majority of TF2's NA playerbase is located in the United States, and I'd wager a guess that the majority of players simply don't have a passport (or enhanced license in the case of my fellow New Yorkers) so logistically speaking that adds another 2 months of waiting and 150 dollars of cost into many player's already tight LAN budgets.
Feel free to reach out to me if you want organizing help, just not sure if it'll have enough of a draw for US players. I know back in the day LAN ETS was a thing in Quebec that had TF2 at some point, so maybe I'm wrong or ignorant, just see that being a large road block.