Bloody marvelous. As is the fact that the Chinese troops are as tall as the Europeans in the pictures. It was Mao’s disastrous policies that (literally) stunted the nations growth
The Chinese aren't a homogenous race, any more than Europeans are.
Northern "Chinese" are taller than southern, and have been for centuries. They are mixed with lots of non-Han and have a wheat and meat diet.
Southern Chinese are far more numerous and are the ones who went to the US etc -- so we tend to think of them as "Chinese". They were notoriously little well befoe Mao entered the scene. Rice with little protein being the diet.
I don't think we can pin this one on him.
I've got friends and worked with people of Chinese stock whose ancestors left 100 years ago for the gold rush. They are universally little.