But what if that man who owns that company, decides he wants to change his business model?

The private part is still important. It's a legitimate fleet of military aircraft that would rival the air forces of many small countries that is directed by a man who really isn't accountable to us outside our borders.

This isn't new territory, it's just that you have to go back a few hundred years to see small groups of private individuals accumulate this much physical force. Just think about some of the disagreements that have occurred over scare resources for responding to the pandemic. Imagine how that picture can change.

It's not that simple. Owning a fighter jet (or even trainer like an Aero L-39) requires both the nod from the ATF, and a bunch of FAA waivers. For a high end jet like an F/A-18 or F-16, It practically requires the Secretary of Defense himself to approve it. Without that approval, Boeing or Lockheed Martin can't provide parts and support for the aircraft.

Notably, Erik Prince of Blackwater/Academi notoriety played fast and loose with weapons import/export/ownership rules, and came very close to being criminally prosecuted for it. Retired Admiral William 'Fox' Fallon resigned in disgust when he realized how far outside the rules Erik Prince was operating.

When Erik Prince suggested letting his private firm handle security in Afghanistan as an outsourced contractor, then SecDef (General) Jim Mattis was dead against it, and blocked it all the way.

Presumably, the same thing that would happen if General Dynamics suddenly decided to change its business model, the major difference being that General Dynamics actually manufactures the weapons you're worried about private companies wielding, and Air USA acquires them.

This just doesn't make much sense as a concern.

They’re not armed jets, that’s an important distinction. Short of flying into something, how would these actually pose a threat?

You didn't read the article? They are armed jets.

You’re right, technically. He has rounds of ammunition for the guns. What I meant was that they’re lacking the missiles. Not that you couldn’t do some damage with the guns, but those are weapons of last resort on these jets. They can’t carry many rounds.

And clearly a man capable of buying fighting jets couldn't source some missiles?

Where by "a man" you mean "a defense contractor that signs billion dollar contracts with the DoD".

If he had bought these on the black market, I’d say yes. But he didn’t, he bought them legally.

If they went rogue or something like that and the US government shut down their supply chain they'd be unable to fly in almost no time. Fighter aircraft take an enormous amount of maintenance to keep in an up status.

This was one of the big concerns if the US/NATO ever went toe to toe with the Soviet Union. With the way modern weapons systems work if they both went all at it, it would not be long before one side or the other had enough of an edge up - just through attrition - that there would only be two options left to the losing side - surrender or go nuclear. You can't have two fully capable super powers fighting one another all out for years any more. You'll run out of stuff that works too fast.

Fighters are export controlled items. Illegal to remove form the US, illegal to show to a foreign national etc. The US has every legal right to enforce how he uses them outside the country.

The article makes it clear that these jets do retain their electronic warfare pods and radar systems.

There would be little point in training against them otherwise.

did you read the article? it specifically puts an emphasis on how these jets hadn't anything removed and even got state-of-the-art ECM pods with them.