The trouble with this is that, as currently demonstrated around the world, you need to keep killing increasingly large numbers of people to maintain this level of control. The argument for apartheit South Africa was always this, and it was a terrible idea. It was the argument for tanks on the streets in Northern Ireland and the argument for tanks on the streets of Hungary in 56.
It doesn't matter because it doesn't justify apartheid, just shows that you don't need to murder lots of people. Having bad countries outsource key government roles to good countries doesn't need to involve any sort of tiered citizenship or segregation.
Current murder rates seem high and are likely underreported. (For instance, Guatemala won't record a homicide if the person doesn't die right away but is helped by aid personnel.)
Further, apartheid isn't a case of what I'm proposing. They were running their own country for their benefit, not as a humanitarian/client setup.
Running a country for someone doesn't mean you need to give citizenship, residency, or even visas to them. It just means you do the math and see that it's obviously less suffering to remove some liberty and self-governance to improve the lives of millions. Over time, slowly give back bits of governance while retaining the right to override. Then take it from there.
It takes some mental gymnastics to allow a situation where innocent people live in fear and can be robbed and killed without reprisals only to claim you've delivered "human rights" and democracy.