I think it IS a form of discrimination. A foreigner should be allowed to stay wherever they
like, unless in a sensitive military area etc, and that rule would apply in many
countries.

Regulations that control the behavior of non-citizens in a nation are legislated by the government. If Trump decides that non-citizens with visas from various countries are not able to enter the U.S. or are afforded increased scrutiny as they enter, is that discrimination? Our 9th circuit court is trying to answer that question now and likely the Supreme Court will have to face it soon.

All regulations that are applied to visa holders and are not applicable to citizens are discriminatory in the broadest sense of the term.

What foreigners are allowed to do in any country is legally the province of that nation. I'm surprised to hear you argue against this precept of nationalism. Australia has 'discriminated' against immigrants throughout its modern history and you have championed those efforts.

Making Caring shell out an extra 80rmb each night to shelter his wife and child in a better quality hotel is a discriminatory regulation. Apartheid it aint.
He is free to leave China at any time. His emotionally wrought financial and legal concerns about parenting and spousal support should have been addressed long ago, prior to nuptials and conception.