I believe he is is imply that "mainlander" is the non-pc term, but I've heard both "mainlander" and "come-from-away" used as slurs.
Interesting. As with many things, words are contextual as to meaning and implied underlying significance.
That and the constant rain/snow/fog/wind pretty much sums it up.
American history is full of immigrants' having their names changed when they arrived here. (My wife's maiden name from her German-born grandfather was Käser, and they spell it the [alternative?] German way of Kaeser. But in other parts of the country we've seen it also written Kaser and even Kayser or Kayzer. And by the way, Käser means "cheese-maker"; it is different from Kaiser, which means "emperor" [according to Google translate]. And my wife's family pronounces it "KAY-zer," not trying to get involved in the whole ä/ae pronunciation thing.)
When I exchanged my California drivers licences for a Mississippi one. The clerk asked my mom's maiden, name which is German. I spelled it for them. No "odd" characters in the name, simply the German spelling. They asked if it was correct. I said yes why? "Thats not how we spell it around here". I replied with "Its German."
For several years I lived on the Maryland-Pennsylvania border. I learned things like what is put inside a turkey at Thanksgiving we call stuffing or dressing; in Pa. it's filling (which to me sounds like a pie).
Of course when I moved from the South to Ohio I had to (1) stop saying y'all because it always made people laugh (they made fun of people who moved from Kentucky to Ohio), (2) start saying "you guys" even to a group of women, and (3) start calling soft drinks pop (it's soda in Md.).
Getting back to Pennsylvania (where they often say "yous guys" (yous is pronounced like you plus an added "z" sound), there was the German name Lutz.
I was told by a friend with that name that in Maryland it rhymes with "huts," but in Pa. it rhymes with "cooks." She lived in Pa., so I asked her why she pronounced it the Md. way. Her response was that she married a guy in Md. and that's where she spent most of her life. (I guess she didn't want to change the pronunciation when changing states!)
Oh, and I forgot to mention the name Cooper. In Pa. it's pronounced to rhyme with "cooker," while in Md. it rhymes with "scooper." (I decided not to say that it rhymes with "pooper" cuz that could be offensive to any Coopers in here.) ;)