I think it is closer to your 3rd possibility. There's also the possibility that they want to show (fake) the supposed power of this system even to their own ci

I think it is closer to your 3rd possibility. There's also the possibility that they want to show (fake) the supposed power of this system even to their own citizens to elevate the apparent reach of the government. Say what you want about rights, but Chinese government is ruthlessly efficient about what it wants done, and it rarely loses (except for the recent trade relations fiasco)