My interpretation of offline is if someone had access to their stored data (ex: blockchain.info is hacked, database is leaked, etc). In that case then 2-FA is pointless. It's only valid when interacting with them as an online service.
Usually you send your password to a service, but in this case encrypted data is "leaked" to a person requesting it. 2-FA prevents from giving this data to strangers (and won't help if the service is hacked, yes)
