> Would you not see it as ethically bad to split the citizens into "true" citizens who can't have their citizenship stripped and second tier citizens who can?

Potentially. I'm not familiar enough with their system to have an opinion. In the US system, I feel like actual citizenship is the hard line. With everything else you're here at our convenience, though I'd say if we were to kick out greencard holders en masse (for some reason) it should just be that they don't get renewed, not immediately kicked out.