I started a new game before thinking of this, but what happens if you reject any new immigrants? Would you in any case? If you did, would they go on a rampage as they leave? Randomly enquiring mind wants to know.
Apparently they can get fighty if they feel favourable of their chances, I’ve heard. By the time I’ve been in any position to deny migrants in my games, they’ve never had a chance and simply walked home
I find myself in a constant need of laborers, so I never reject new migrants 
I’ve rejected a few and they just leave far as I know.
Have you ever had more people than you need in this game? It is the only reason why you would not accept them but somehow I think that’s not the case 
I’ve had Pop immigration exceed housing, does that count? Easily fixed by housing, or letting them freeze to death. Not going to reject any until I get to T3.
Same, have done it several times, no questionable actions done.
Never happened to me past years 1-2 