> When do they stop being immigrants?

Never?

> If you think people who waited more than a decade and paid a hefty sum to affirm their will to be citizens are second-class (or maybe even traitors!)

I don't think so. Do you?

(Edit: I don't object to using 'immigrant' in a different way. But when someone said that in the places with more immigration there will also be more immigrant voters it was pretty clear in what sense the word was being used. Dumbass.)