No, not yet, but as Lorentz said, I don't need convincing
othering is bad. I need convincing that the usage of "illegal alien"
is othering, or - depending on your usage of 'othering' - that it is somehow
more othering/bad than any of the other examples given.
To me, the connection is blatantly, painfully obvious. I really don't understand how you could possibly believe that it isn't. No, honestly, I really don't.
For lack of other apparent common referents, I am forced to go to pop culture for an example. In the movie
Alien, the eponymous Alien isn't some nice guy who trims the bushes. It's a monstrous, murderous creature that kills as many people as it can just because it enjoys that sort of thing. They could have called the monster "Xenomorph", or "Ravenous Bugblatter Beast of Traal", or something else, but that wouldn't have conveyed the sense of weirdness, the sense of differentness, or the sense of dangerousness that the writers wanted for their monster. No - for that, they had to go with
Alien - a word that, above all else, conveys that
this thing is not like anything else that we are familiar or comfortable with, or feel safe around.
In short, I have to say - with all possible respect - that if you do not understand why calling a person an "alien" is a method of othering them, then despite your claim you do not understand what othering is.
It may once have been true that the word "alien", like the word "retarded", could be used non-perjoratively, but it's been at least forty years since that was true. Some day it may be true that the word "immigrant" is similarly changed, but until then it is a more acceptable way of describing people than calling them an "alien" is.