An easy first step would be to not hold a sci-fi conference in a totalitarian dictatorship. Why couldn't they have just held it in Japan or South Korea or Taiwan instead?
In fact, this whole debacle has hurt them the most since it seems many/most Chinese authors were excluded by default since the amateur self-appointed censors couldn't actually be bothered to figure out what disqualification criteria would be, just that it could be "sensitive to China."
The organizers are just whoever won the vote to run the conference that year. There's no actual organization that persists from year to year.
Otherwise I could announce a Worldcon unilaterally and no one would have the grounds to stop me.
The Chengdu bid won the vote legitimately. They would have been massively overstepping their authority to try to prevent it. It's unlikely they could have even won a court case if they tried to prevent it.
One could argue that when parties involved have so different population numbers, probably using the percentage of votes relative to a country population, instead of just number of votes would be a better solution.
...as opposed to professional government-appointed censors?
The problem is one of effective power: do you tell people who live in these regimes, "sorry, you cannot participate in this culture because your government is bad." How much pull do they have to change things, especially this sort of thing? Or do you say "you can participate, but only at a lower tier." Either way is going to put some people into an out-group. Maybe that's the right thing to do--paradox of tolerance, for instance--for the rest of the people in the group or culture. Maybe it isn't.
I know it would hurt pretty badly to be a science fiction enthusiast in China, perhaps even someone who really does not like what their government does, and not be able to participate. On the other hand, it hurts to be potentially on the list for your work's most prestigious honor, only to be "disqualified" because you "might" have written about something that isn't permitted in the host country you couldn't have predicted.
Yes. Sorry, that's how it goes.
If I'm running a dance competition, I should not hold the award ceremony in a country which outlaws certain types of dance, lest they arrest some of my attendees.
Similarly, if I'm running a literature competition, I shouldn't hold it in a country that outlaws certain types of literature.
This isn't about trying to change anything per se, it's just practical.
The Olympic Committee aren't quite as awful as FIFA, I don't sense plans to hold a winter games in Qatar for a fat bribe for example, but they're pretty bad.
I'm not sure how you can tell. They're both completely rotten, as far as I can see: not an honest person among them.
Only the Chinese people can change China.