but Air Force ordnance is hinted at. Sheesh!
Yes, I noticed that. However, remember that there are lots of mil surplus bits and pieces that are completely inert (or not even ordinance) which might not be either easily identified, or clearly still inert, which an investigating ATF officer might run across. Generally, they'll call in someone with the experience to make sure they're not about to level themselves, the house, or the city block.
There was an antique shop I loved as a kid that had an enormous WWII fighter plane auxiliary fuel drop tank strapped to one of the front porch posts. It looked for all the world like a bomb of the sort Wile E. Coyote would have tossed at the Road Runner. But it had never been a weapon of any sort, and if I could have ever scraped up the cash, I could have carried the thing home and hung it from my ceiling.
You can certainly expect that the ATF would much rather "unnecessarily" call in an EOD specialist to cart that thing off than risk a guess that they weren't about to make the evening news in a really big way.
And sometimes, as Dr. Freud would say, "a cigar is just a cigar." I knew a lovable old fellow who lived in a state-funded senior center for the last couple decades of his life. Ex-military guy who loved shooting, especially BIG booming guns, and always had a goofy grin for every one of his pals. When he passed away, his heirs discovered that one of his prize treasures was a very live, very old, grenade.
You just never know. Eventually there will be charges filed and then we can all find out what the big deal is.