He assumed that Google assured him that his current data would be safe. But saying that your account will move into read only mode doesn’t equate to keeping those much TBs of data on server forever.
Though I have a question. Was this unlimited service that Google offered was a one time payment thing(seems unlikely, since only couple of cloud providers like pCloud do so and that too on a much lesser scale) or a recurring subscription thing? If it was the later, then it is naive to believe that a for profit corporation would keep that much data without raking in money.
Iirc it was a subscription, but I could be wrong. Having unlimited data with a one time payment doesn’t sound like a Google thing to do. There are running costs.
Presumably it was GSuite/Google Workspace. While they advertised unlimited storage if you paid for 5 accounts, it wasn’t really enforced so you could pay something like $20/month and get unlimited storage on G-drive. There was a daily cap on how much data can be moved, but that’s fine for hosting incremental backups like many that took advantage.