And why exactly is the bare storage of these not encrypted? I would expect, at the very least, that the data is encrypted using customer-specific keys.
So we can conclude that it was not. If the disk was encrypted (with decent passphrase/key) there is 0% chance that the article wouldn't mention it.
They also wouldn't have bothered to get the disk back from the YouTuber. Why would they if the data is unreadable anyway?