I agree with your point on #3, but I think it'd be pretty disingenuous to suggest that your proposal for how #3 manifests is the most common way it manifests currently. In other words, at least in American media, it feels like it's the opposite of what you've suggested: media must contain gay characters, or contain characters who are not heterosexual in the traditional sense, and that other representation check boxes must be met. Now to be clear, I think what you've suggested for #3 is also bad. I think it's bad for outside forces to twist art to ensure it follows the "correct" social values, and I feel this way regardless of whether or not I agree with the social views present in a given piece of art. I also agree with that you the Chinese studio is not being a-political here, but instead is saying something more like "don't infect our Chinese social values with your modern progressive western values." I think people are forgiving of this mostly because they're so exhausted by the incessant push for modern media to have the "correct" progressive values. (I'm not suggesting that people _should_ be forgiving of the Chinese company in this case, but just describing why I think it's happening.)
For #2, I think it's a lot more of a grey area. In principle there's nothing wrong with a piece of art pushing its own social and political agenda, but it can become oppressive if it becomes too widespread or forceful. I can imagine that any era prior to the late 90s, the refusal to show anything other than heterosexual and traditional relationships on screen must have been frustrating for some folks, even if they did not have any issue with traditional heterosexual relationships in principle. The same could be true now: an audience could exhaust on having the same moral message crammed down their throat, even if there's nothing particularly wrong with the given moral message in piece of art when taken as a singular instance. A non-social and non-political version of this might be similar to super hero movie fatigue. The first run-up of Marvel films was a lot of fun, but after another decade of them and 60 more films (or whatever it's been) I'm much less tolerant of each new entry, even if I would have enjoyed prior to becoming so over-saturated. And, as I tried to outline in my initial comment, I think there are better and worse ways to go about this. Something like Pan's Labyrinth is aggressively anti-fascist and pro-feminist, but it's universally loved because it didn't put its message above its art, and didn't cram its message down its viewer's throats. It did not alienate its viewers by attempting to winning culture war points, but instead told a beautiful story.
Lastly, I'll say that I agree with a lot of your points, and I think hiding behind BOTH SIDES of this debate is an elephant in the room: people are leaning on principles, but often just find the speech itself to be objectionable. In other words, if they agreed with the speech then scenarios #2 and #3 wouldn't bother so many people as much. I think this is sort of unavoidable when it comes to contentious cultural topics, but I've done my best to stick to the "principles" side of things here. It's important to be open minded here, and understand that the free speech principle (eg: an artist is free to create any work they want) should be separate from my perception of the art. (eg: I really hate this piece of art because of the social values present in the art.)