I think it's likely that Flickr has a way to recover the data but the front line support personnel don't, and they don't want to have some dev spend a few hours to fix a single customer's problem, even if it was Flickr's mistake.

Reverting a full db should be straightforward (stop the db server and revert a dump).

For a single account it's more of a pita.

Retrieving all the datas associated with one account, put it in a format readable from the production environment and recommit all the changes while dealing with the potential errors and inconstencies seems quite a huge deal.

Messing unrelated data in the process would also be a nightmare.

Of course, not deleting anything from the start wouod be the way.

It's trivial in Oracle, just do a Flashback Query. You would just need to support that in whatever front end interface the customer support people use.