Is it? If so why? If not, why isn’t it?
I think it’s a good enough reason even if only 2 national govts didn’t prohibit any freedoms of movement and an additional govt allowed freedom of emigration only or freedom of immigration only. That said, the more nations that allowed total freedom of movement, the more Gresham’s Law applies, but I think a good example would be set and followed as long as one nation didn’t prohibit any freedoms of movement.
no problem.
the reason immigration laws exist is because government wants to tax everyone
As a non-immigrant alien on a visa, I can say that it sucks not being able to engage in mutually beneficial trades of labor for wages in this country or to start my own business. No, really, it does. If I could have started making money at like 14 then I might have a much nicer life later on. Stupid laws. And I’m not even kidding.
Youre a smart guy, you should have a hobby of buying and selling on the internet peer to peer. You can easily keep your wealth in tangible goods, perhaps they arent convertible or stable, well you learn lessons. I have a friends who have made gooooood money online, one just kept flipping automobiles until he had a few nice cars.
As an alien here, I have to take particular care to remain on the good side of the law lest I want to be deported 
Could you explain how Gresham’s law applies to labor in the first place? I’m not sure that it does.
^
Seconded.
I don’t see how bad labor drives out good labor if the bad labor is overpriced by the government in labor exchange. O.o
Gresham’s Law applies to labor because govt imposed immigration restrictions artificially raise the value of bad labor
Gresham’s law applies to situations where governments enforce a fixed exchange rate between two currencies which overprices one and underprices the other, such that the former “drives out” the latter. Immigration restrictions just bestow a restrictionist wage rate for domestic labor at the expense of foreign labor.