It is completely valid to not finish a game because you disagree with the ending/s, btw. People walk out of theaters, people leave TV series mid-season, people put books down before the last pages. While the devs do have all the right to treat their story as they like, the consumer has the power not to consume said product.
So if you don't want to finish the game while Karlach's endings are as they are, it's all fine. I did that too.
Oh, and it is completely okay to voice your disagreement as well. It's up to the devs now to do what they want with that information.
