I have a hunch that the currently sole owner just wants to do this until retirement. GoG is financially stable so there's no pressure to increase revenue.
I see no simpler explanation why someone would buy out a subsidiary like that.
All in all, GoG thrives on people being sentimental and it's totally in character for the owner to be sentimental as well.
Younger generations grew up with DRM already present.
Same with anti-cheat really. The most common reason I hear people don't make the switch to Linux is that certain games work only on Windows due to the type of anti-cheat they use.
I see no simpler explanation why someone would buy out a subsidiary like that.
All in all, GoG thrives on people being sentimental and it's totally in character for the owner to be sentimental as well.