RWarehall: Call of Cthulhu: Dark Corners of the Earth involved legal rights issues. In situations like that GoG is forced to act as soon as they are notified.
PainOfSalvation: Then it shouldn't have been in the store in the first place since the fan made patch with few tweaks made the game in working condition. Legal rights should be checked thoroughly before the game hit the store.
Granted, but legal rights can be complicated. Just look at Star Control. At one point both Fred and Paul and Atari both thought they had the distribution rights. Sometimes one person owns the rights to the game and contents, but another owns the copyright to the title through an exclusive license. I've heard two conflicting stories about COC:DCoE. One involved an upset modder and another that Bethesda filed the complaint.
GoG clearly thought the publisher had secured all the necessary rights to publish it, but that appears not to necessarily be the case. Just think about all the no-CD cracks and keyword bypasses used on some old games. Can you even find the original author for those? And does that really violate fair use when they have been offered up for free for years? Is crediting them enough, or do they have a right to demand a royalty now that it is being re-released with your patch despite the fact the modder has been offering it for free? It can be quite complicated for old games.
If it was Bethesda, they might have purchased trademarks for the game somewhere. I don't have the answers to these questions, and it's even possible there is no single "answer" because some conflicts can only be decided through the legal system.
The short of it is that sometimes, legal rights will get disputed resulting in games being pulled from sale. This has happened on every platform and is not unique to GoG.