[schoen]

I think the quarrel here is about the definition of "legal tender". Its literal meaning is not "reliably redeemable at a bank", but rather "required to be accepted by anyone as payment of a debt". These can diverge easily. For example, I remember that Sweden changed its banknotes a few years ago, but the old notes were redeemable at banks for a set period of time. The old notes were definitely not legal tender in the technical sense because private individuals and shops not only were not required to accept them, but actually did not accept them anymore. That doesn't work well with the definition of legal tender!

However, the old Swedish notes had not lost their value because they could still be redeemed.

In a formal legal tender situation, you could to some extent require a private party (within the relevant jurisdiction) to accept the notes in payment of a pre-existing debt. You could contrast this with "having value", "being redeemable", "being in circulation", and "being widely accepted", maybe.