I'm not sure what you're talking about. First, it's fucking boring. Pixar is dead.
But to pretend this is somehow about "immigrants" and not a hamfisted story about racism and "diversity is our strength" is just being purposefully obtuse. You can try to pretend that media isn't a reflection of the current culture but you'd be an idiot.
It is pretty ironic though, because the whole premise is so retarded that they overlooked the fact that "race mixing" in the context of this movie will literally kill you. Maybe it's secretly based?
Read a review and they made a good point in that they already made this movie, better, with Zootopia.
This will probably be the last Pixar movie I ever attempt to watch. What an amazing fall from grace.