Apparently he bought them from whoever SEGA hired to liquidate the office. From the looks of it he's also a bit of a ... well ... simpleton. Lots of empty threats to police without even hiring a lawyer, i.e. he'll just be ignored by police and the courts.
There's an article with some more info in the replies: https://www.timeextension.com/news/2025/09/sega-accused-of-using-police-to-recover-nintendo-dev-kits-it-had-negligently-disposed-of
Apparently he bought them from whoever SEGA hired to liquidate the office. From the looks of it he's also a bit of a ... well ... simpleton. Lots of empty threats to police without even hiring a lawyer, i.e. he'll just be ignored by police and the courts.