(c) Dissolution Event. If there is a Dissolution Event before the termination of this Safe, the Investor will automatically be entitled (subject to the liquidation priority set forth in Section 1(d) below) to receive a portion of Proceeds equal to the Cash-Out Amount, due and payable to the Investor immediately prior to the consummation of the Dissolution Event.
If you wind the company down, you would/should try to make your investors 'as whole as possible'.
Debt implies that at some later date YC could come asking for their $375k back. A SAFE is not debt.
If your company is running and does not end up raising more money that SAFE should just sit there waiting for the day that you do (which may never come).
There's no maturation date on a SAFE. This is all in the "User Guide" YC publishes for these instruments. The text of the SAFE refers to it as a "converting security". I'm sure there's an important distinction to be made here, but for the purposes of this discussion: if you never raise a round, the issuer just gets their money back (if money is to be had after senior claims).