I think he brings up a point. Legal aliens should be called legal aliens
But no one does that.
We call immigrants "immigrants". These people use proper paperwork and immigrate to the US legally. They get green cards or whatnot and may eventually become US citizens, if they haven't, you know, broken the law or anything.
We call illegal aliens "illegal aliens" because they come from a different country and because they have come here illegally. They should never be US citizens.
the proper term is Registered Alien
a green card is a Alien Registration card...
it has a number which is later annotated on the right top corner of the Naturalization document when the immigrant becomes an American citizen...