Well, I don't think anyone thinks many non-Chinese speaking Americans are going to move there. I think this is targeted at the top tier of immigrant talent, particularly people who may have come from China to the US for school and stayed. For them the equation is more complicated than the one you present, particularly if they feel unsafe, or even unwelcome in the US.
Just to put some perspective on this, as I write this there are 328,547 current graduate students in the US from China. Ten years ago nearly all of these people would have remained in the US -- and these are valuable people to have. Today far fewer do because it's become harder to get a green card, and opportunities.
Likewise there are 166K Indian graduate students in the US, many of whom China would like to lure away when they graduate. It would be better for us that they stay here, but China would very much like to obtain the services of these bright young people with shiny new graduate degrees from American universities.
I'm not talking about the cheap contract labor your IT consultant uses to run your Exchange server; I'm talking about the intellectual elites who create technologies, companies, and jobs. China may be a police state, but that doesn't make them stupid; they value these people. America... not so much. In fact there are places in this country where being an educated white American makes you the object of suspicion.