AFAICT, Midjourney has no shareholders and David Holz is the farthest thing from a slick CEO. He’s a big dreamer hippie dork. He made all the money he cares to have from the sale of his previous company and now just wants to work on fun research projects. The goal of Midjourney is to bring creative power to as many people as possible.
Whenever politics or other controversial topics come up, the MJ teams tries to stay out of it. They just want a welcoming space for all sorts of people to collaborate and create. Lots of people complain that they don’t allow porn. But, as a result, a millions of people who are not just horny teenage boys enjoy hanging out on the server sharing and discussing art that is not just pics of sexy women all day every day. Looking at you, unending parade of unfathomly huge boobs on https://mobile.twitter.com/search?q=%23StableDiffusion
David seems to think that since ridiculing politicians in China is taboo, having people ridicule Xi on MJ would make it unwelcoming to people in China. He wants them to feel comfortable collaborating with people all over the world on MJ. So, prompting Xi is blocked. That’s all there is to it.