There is an enormous gulf between most kinds of harm one can do to someone in a different country on the other side of the world and dropping part of a rocket on them.
Nobody agrees a priori to China’s assessment of their economic value.
Even if you take the US assessment of the value of a person's life it probably doesn't make sense for China to do anything to control the entry of these stages.
Every action we take imposes risks on other people.
Economic models are one of our best tools to use in weighing these risks against each other and the costs of mitigating them.
(OTOH: China's cost to mitigate most of these risks would be, generally, pretty small... It's a cost of being in the space game, IMO.)