I hate to blame the end user, the consumer, but yeah clearly at least some blame is to be put onto them. As outlined in the article.
To trust Microsoft cloud services & make that a single point of failure is exceptionally foolish....and they were moving all this data off of multiple old drives & consolidating onto one big one. Why not copy-paste? Why did they actually cut-paste, move all that data into the cloud?
If it was truly so "priceless"...just make another copy? Keep everything, always, until other copies are made.
I feel bad for the guy, but come on. That was a problem they themselves created. Clouds are for rain. Assuming this person is at least 40 years old (30 years of photos & work) if not significantly older, they are more than old enough to know better, to just blindly trust cloud storage with everything.