As it's said in the postmortem, they are agreeing that they should have stated in a more obvious way that the backups availability was not contractually assured.
The postmortem says "we don’t provide a backup product for customers" while the docs describe the snapshots as a backup (see screenshot from my higher level comment). This is the disconnect for me that I'm sure is causing a lot of the frustration they are hearing from customers. They are not accepting that they sold the snapshots as a backup and this is disappointing in a postmortem where users are looking for empathy, acknowledgement, and a path forward.