It could be argued that bitcoin’s value can’t be permanently destroyed as long as the data of the original blockchain is still around, because at a later date (after civilization comes back) the community could reset the blockchain to the point before all the bad stuff happened. There might be widespread disagreement about precisely what block everyone ought to reset to (e.g. was it directive 312-A-1 that destroyed bitcoin or was it 315-C?), and different choices of reset point among different sub-communities would lead to different branches (different daughter currencies). If you had access to your wallet from the original chain, you’d have access to wallets for each of these daughter currencies, so it’s not clear how much value you’d lose.
All we can say for sure is that an individual bitcoin wallet’s robustness against societal collapse depends acutely on a lot of unknowns about future peoples’ preferences and the precise way in which things collapse, whereas gold doesn’t.