It would definitely work (and when dealing with petabyte levels of data the simplicity of only having to delete the key is convenient).

We’re leaning toward the dual-layer separation I described though (metadata separate to content) mainly because crypto-shredding means every read (including regulatory reconstruction) depends on a key store.

In my view that’s a significant dependency for an audit log whose whole purpose is reliable reconstructability, whereas dual-layer lets the chain stand on its own.

Your point about developer mistakes is fair. It applies to dual layer as you say with your example, but I’d say crypto shredding isn’t immune to mistakes because (for example) deleting the key only works if the key and plaintext never leaked elsewhere accidentally in logs / backups etc.