Well, like I say, it was well documented that this wasn't a great idea and I'm not responsible for the outcome, so I have no problem sleeping.
BTW, I mistakenly thought it was a NAS unit he was backing up to because he mentioned NAS in the same breath as backups. But it turns out it's another thumb drive. Still not encrypted though. This is easily described as the old you can lead a horse to water.... Or is it you can't fix stupid?