There is an important piece here.

Robotics.

Robots in The US, work just as cheaply as the robots in China.
However, in China, China owns the company, owns the robots.

The US is much more stable in property ownership. You might even say that in The US the corporations run the legal system.

There is already a movement of bring industries back to The US at robotisizing them. Now, Chump is just tweeting his horn about it.