Mundane explanation: "UFOs are advanced technology from some other country like Russia or China."
If that was true, the technology is so advanced they could overwhelm our military easily. We also know due to Thucydides trap it's in China's interest to start another large scale war. You'd have to assume world leaders don't want their country to become a superpower (nor want the freedom that comes with making their fiat money the new reserve currency) or you'd have to assume some tiny country like Monaco secretly has military technology far surpassing America's. It assumes way too much.
"UFOs are advanced technology from America itself, this is just another disinfo campaign."
While slightly more plausible it falls apart when you think about it. If the purpose of the pentagon admitting UFOs are real was to intimidate, it would make more sense to say they actually are in control of this technology. If the purpose was to appear weak to be able to surprise enemies later, it would make more sense to prevent the media from dwelling on it at all.
"UFO confirmations by the Pentagon are completely fabricated and the tech doesn't exist."
Definitely plausible. The feds need to justify all those blank checks they write to themselves and 'UFO research' is as good as anything else. Furthermore, commoners will be slightly more pacified about hyperinflation and other real crises when they think aliens/gods are the on the way to save them. We know they've done things like this before and Obama legalized propaganda against US citizens in the 2012 NDAA. This is the theory I want to believe.
"UFOs are normal technology and this really is an indictment of an incompetent military."
This is the theory I actually believe. That Elizondo guy just isn't someone I can take seriously. Parsimony achieved.
Or...
They’re an earth native species who advanced far beyond our technology today, realized the cyclic, cataclysmic nature of this planet and figured out how to live either off world or under the ocean. Both are equally plausible.