thus every option that allows a player to curate a game to their preference is a good one.

Generally I'd agree. BUT..

Assuming this sex scene is a key component of the narrative, editing it out would detract from that narrative, correct? Maybe this is an argument from elitism, but I don't think we should cater to people who have so little appreciation for creative independence and artistic expression that they think artwork can and should be subject to democratic input from the audience.

What you're advocating is, if pursued to its extent, a degradation of art's inherent transformative power. We're not talking about options to change difficulty, graphics, mechanics, etc. It's nice of the developer to be so caring about people's psychological issues, but the "fascist" nature of art is one of its most essential attributes and it shouldn't be compromised, principally speaking. Art is a vehicle for individual expression and one of the most important catalysts for social and cultural change in society because it's a way to communicate transgressive concepts to audiences. What is "objectionable" is relative and often the only way to change people's views is to forcibly expose and familiarize them with material they initially believe is objectionable.

First we edit out profanity, then we edit out blood and nudity, then we edit out sex scenes, and on it goes. If you really think video game presentation is so democratic, then where does it stop? If it was possible, should the developer offer an option to turn off all violent acts in the game? To turn off all drug use? To turn off all "stressful" conversation that insinuates conflict?

If audiences were given infinite options to curate games to their preferences, as you advocate, the potential for creative exchange between the author and audience would be lost. There'd no longer by any power to provoke or compel reflection. Audiences would just open up their options menu and make everything exactly how they like, just like we have with cable news today: everyone turns on the TV and picks the news channel that conforms to and caters to their preconceived biases and worldviews and all potential for education, provocation, and transformation is lost.