What's going to happen to the money? The only reason I can think of to auction the bikes instead of donating them to another museum is that whoever controls the organization is planning to basically appropriate the cash.
'National' and 'Museum' are doing the heavy lifting here to make you feel this way. Its a privately owned collection incorporated as a non profit to avoid taxes.
It's a cheap way to get a veneer of respectability. The best example of this I know of is the "National" leprechaun museum. https://www.leprechaunmuseum.ie/ . At least they had the good taste not to put it in the domain name.
Is this possible? Their own website says “With your generous support we have expanded the list of motorcycles on display from 40 to over 500.” If that means many of these were donated, it doesn’t seem to be a private collection.
Maybe the non-profit is the museum without the collection, and the museum just shows non-museum owned stuff?
The owners have the right to do sell the bikes and collect the cash. They can spend it for anything they wish - to start a new venture, to enjoy life, to light it on fire, whatever. That's the deal they entered into when they chose to become the owners of this collection.
It's no different than if an individual sold a house or a baseball card. They can spend the cash however they like.
While true, I don't think anyone has ever been prosecuted under this statute for performative burnings. From what I could find prosecutions seem to be concentrated on fraud.
Yes, the internet always struggles when registered nonprofits with what must be millions in assets “go under” in ways where it is unclear what is happening to the assets.