Did anyone consider he might be going on a hunting trip?
If a person wants to hunt in a location that is best reached by air travel, then how are they supposed to transport their equipment?
Good reasoning. And the bag limit is 37 so he brought 37 guns. Yep, makes sense.
Or picking up or dropping off someone else.
Did anyone consider he might be going on a hunting trip?
with 30 handguns? Not likely. That doesn't mean he was necessarily doing anything nefarious, it just seems unlikley.
In most places, you follow the rules about how they must be packed, and then declare them when you check your bags. It's perfectly legal.
I once inadvertently transported a full box of .45 ACP in my checked baggage. On the return trip, I declared it. They said, "is it in the original box", I replied "yes". They said, tell the TSA guy at the screening machine about it and go board your flight. I did, he said "OK", and I was on my way.
Guns are slightly, though not much, different. (They need to hand inspect the containers, since any gun shipping container is likely to be full of nitrates that would set the sniffer off, apparently loaded ammo won't).
Thirty-seven? What was he hunting, a small country?