No, it is a threat to peace and prosperity in Mexico. Trade between the US and Canada didn't change much with NAFTA, and if NAFTA went away, it probably would revert back. What would change is trade in and out of Mexico. As Mexican access to Canada becomes much more complicated if it needs to transit the US first, and Mexican trade to the US also likewise suffers a major blow.
Of course, Canada also suffers because they run into comparable problems when it comes to trying to transport goods to Mexico through the US.
Disruption of US <-> Canada trade is a MUCH bigger threat to Canada than anything involving Mexico.
Further, Mexico going down the proverbial toilet isn't much of a direct concern for Canada in the first place because they don't share a border with Mexico, that will be a problem for the United States to deal with.
But that is international politics, Mexico has to try to sell their own interests as being in the interest of everybody else. In this case, there would certainly be an impact for the Canadians, so he's correct in that much. However, he is overstating it significantly.
Besides which, Canada isn't a "labor threat" to the US like Mexico is. Labor is more expensive in Canada(well, depending on the exchange rate at the time), and they're on par with us technology/automation wise, so they're an "Apples to Apples" marketplace for us. As such, Trump is going to be playing softball with them, they're "not a threat" in the context of foreign trade//American Jobs.
Mexico on the other hand, is another matter entirely.