Yeah, those critiques of the franchises it mentioned are true, and broadly speaking it's accurate but it's tracking trends in zombie media. That doesn't mean all zombie media that comes out now is allegory for immigrants.

I haven't played Dead Island 2, but a cursory read of the plot seems to me like it's just playing on pandemic fears. They don't tie zombie outbreak to global migration like World War Z does, rather it's just some scientist who discovered that all humans have a gene that's going to make them all become zombies unless he essentially vaccinates them by giving them an inactive version of the virus. It's the opposite to what you're saying really because all of humanity is affected by this 'expiry date', not just certain people who need to be stopped from migrating. It's set in a quarantined L.A. It just seems like they're exploring the 'greater good' of quarantine and vaccines to me. I guess there's elements of eugenics in that some people are pre-immune to the zombie gene but I wouldn't assume that was their intention.

Perhaps you could read into problematics of killing hordes of people defined as not human if you wanted to, but I think that might constitute being a joyless leftist. (I am one of them)