Not saying its actually what happened but I would ask how he knew about the data.

Statistically, it should have been a random port scan that got in but since he‘s from the same country, he‘s either professionally or privately connected I assume. He either worked there in IT function, visited as a patient, dated an employee, etc.

So in other words, he‘s not a master hacker but probably stumbled across this. I had this with a webspace provider once were I could see all other customers folders when I used ssh instead of the web interface. I couldnt access them but I got a wiff of how stuff like this happens. 99.9% of their customers are inept at IT stuff so a mistake in ssh would never come up since customers wouldn’t use it and in that one case, they overlook it.

So, this might have been his first hack ever and it probably took a long time til he even understood what he had in his hands. Thats why I dont do stuff like this, I‘m prone to such mistakes as well. Most elaborate scheme imaginable and cc it by mistake to someone I know.