its possible. just find a counterparty who wants to take the other side of the bet.
people short unshortable assets in finance all the time by getting the bank or a marketmaker to take the other side in an "over-the-counter" (OTC) agreement.
You just make up the rules and there's a signed document.
i.e. "bets backed up with legal documents".
And... I, for one, would probably take the other side of the bet against Tim Ferris in the short term.
Hard to short a guy with a massive following. He can sell pretty much anything to his loyal fans. And there are a lot of them. You'd be better off shorting Tesla and Elon musk. Take away all their government subsidies and all you're left with is hype.
And a car that seems to have achieved something that others haven't, is licensing its technology to Toyota, and is selling cars that people want and are excited about. Other than that, yes, just hype.