Really weird decision. Though it was added to GOG about 3 weeks after that article was written.

And GOG has its share of slop (e.g. a dozen Whale Rock Games which have obviously fake reviews).

The rejection of Opus Magnum got a lot of attention at the time, which probably caused GOG to reconsider. But most developers don't get that kind of attention, if a game of theirs is rejected. I've seen multiple developers of games that I like, saying that they've given up on GOG because of the curation