Wait there are two odd parts to this story.
(1) A firearm was in checked luggage on a flight from Canada.
(2) He had available ammunition for the firearm.
If you have ever gone hunting in Canada from the USA, you know that crossing the boarder with a firearm is not a trivial exercise. Last time my uncle tried to take a handgun into Canada while driving the Al-Can highway to Alaska he had to have a handgun, placed in a sealed container that had Canadian seals affixed to it and if he had broken the seal, he would have been in really deep trouble and they checked it on his leaving Canada. As to the shotgun he took that was less difficult to cross with in a motor vehicle, but still a big deal. I have a friend who got stopped at the boarder with an air rifle in his RV and they made him turn around and check it with the local sheriff before entering Canada.
Handguns are not something that normal people regularly own in Canada. I would wager that if the firearm were in checked luggage, it would be flagged and have special handling and screening.
Normally a firearm and ammunition must be stored in separate and locked pieces of baggage. I would be surprised if TSA (or the Canadian equivalent) didn't spot ammo or the firearm on their baggage screening.
I find it hard to believe that a bag containing a firearm and ammo would have been tossed out with regular baggage at the airport terminal in Florida.
I don’t care what spell check says. There is no “a” in border.