The submission doesn't state it explicitly, but a firm's debt enters its Enterprise Value at its market value, not its nominal value [0]. If an openly traded company (a company that has non-zero shares) had a market capitalization of zero dollars, the market value of a bond issued by it would be, most likely, also zero, or very close to zero, even if its face value were non-zero.
If the market values a firm's stock at zero dollars because it isn't expected to increase in value nor to pay any dividends at any time in the future, then it wouldn't be expected to pay back any of its debt either, and so the market value of its debt would also be zero.
If the market values a firm's stock at zero dollars because it isn't expected to increase in value nor to pay any dividends at any time in the future, then it wouldn't be expected to pay back any of its debt either, and so the market value of its debt would also be zero.
Hope this makes things clearer.
[0]: https://en.wikipedia.org/wiki/Enterprise_value#EV_equation