As noted by others, it is indeed a book promotion [1] The "petty criminal" has himself published a series of books [2]
However I take issue with your argument with "hacking would have been easier". DCs in the 2000s were (and to a large extent, still are) extremely easy to access. If the data at stake were actual "banking" data, in the 00s, it could have been still largely "air-gapped" (in the loose sense) from the internet. Hacking would have required a lot of lateral movement. And experts.
Hence, a large trail. Arguably larger than "hey bobby, here's a wad of cash, go in that building, steal these boxes in corridor A"
I also take issue with the "physical locations of DCs are still secrets" angle of the article.
Anyone working in a DC-adjacent industry and is curious enough can locate the back-entrance to any DC they have some business with. If it is a secret, it's not a well kept one (for good, operational reasons!)
Sites like DC Map give you the exact physical location, for instance.
The story is entertaining but it has clearly been romanticized.
[1]https://us.macmillan.com/books/9780374619794/cloudthief/ [2]https://www.amazon.com/gp/product/B0C9YVP3X2