Stacking those together ("X is essentially an Y, 100K of Y are essentially Z, 100K of Z generally behave like U") is what got us the 2008 financial crisis.

Put and call options are about as basic as it gets in finance.

Though, the more and more I think about the grand-parents comment, the less I understand it:

With debt, you can go into default: so all your assets go to the creditor, instead of you paying. That's like buying a put option, not selling one.

Yeah you're right. It should say something like the payoff of debt owned by the creditor looks like being short a put.

No need to be dismissive - simple financial instruments are only obscure to those who willfully remain ignorant.

Your parent post's statement is a reference one of the basic financial models in asset pricing literature, the "Merton model" (Merton RC. 1974. "On the pricing of corporate debt: the risk structure of interest rates." J. Finance 29:449–70)