Why is it even necessary to show a political map in this movie? I haven't seen it, but I doubt that territorial claims by China are part of the story...
Because China demands gestures like this to give films access to the Chinese market, and Hollywood in turn grovels.
I can think of quite a few popular films, distributed in China which don't feature any maps.
I think self-censorship is fairly well documented when it comes to Hollywood and the PRC at this point, but do you have something to back up that demanding “gestures” such as this are commonplace? If so, it is news to me at least and I would like to read more about it.
There was a great book, Red Carpet: Hollywood, China, and the Global Battle for Cultural Supremacy, that had both examples and which talked about how the idea that Hollywood is kowtowing to Beijing is coming to an end... not so much because of Hollywood, but because China has been working hard to build up their film industry to a point that they have regular domestic features and don't have to depend on foreign films. So while some studios still likely self-censor in an effort to get China distribution, as that avenue is increasingly closed off regardless of the film content, that self-censorship may go away.
There isn't, especially not for something that stirs up regional drama like SCS maps. PRC censors rather there be no politics at all.
One of my personal favorites is John Cena groveling in Mandarin because he mistakenly called Taiwan a "country".
And those who don't have their careers destroyed - how often do you see actors talk about the plight of Tibet after Richard Gere was basically run out of Hollywood?