I don't know this game, but I hate it when companies say "After receiving many messages from gamers, we have decided not to list the game in our store."
Aside from it being a select few gamers that will have sent messages (whilst we here at the forum generally get ignored, and we are actually GOG users unlike the messages like most likely got on Twitter.)
They also didn't explain why, but upon searching it turns out the game was also removed from Steam due to a backlash from Chinese players due to a controversial reference to Xi Jinping.
[url=https://en.wikipedia.org/wiki/Devotion_(video_game)#Controversy]https://en.wikipedia.org/wiki/Devotion_(video_game)#Controversy[/url]
I'd say its likely the same reason that GOG have blocked it.