Why does it suggest that?
China has only been seriously trying to cut back on coal for ~10 years.
All it shows is that coal is cheaper than nuclear and that to a rapidly industrializing country cheap is more important than environmentally friendly.
On the other hand the US is shutting down plants and decreasing overall capacity.
China, as you observed, has no qualms about "environmentally friendly", so according to America's nuclear proponents, China should have more nuclear than us, not less, since it's cheaper. This is not the case, ergo their argument is flawed.
Your argument doesn't really make sense.
Nobody is arguing that nuclear is cheaper than dirty coal.
Proponents argue that it's cheap and orders of magnitude more environmentally friendly than burning dirty coal.
China is still very price conscious and are building out nuclear in an effort to reduce pollution - proving that the Chinese do believe nuclear can be done cheaply and safely.
They have not gone all in on nuclear and are exploring as many alternatives to coal as they can.