You're questioning their means, but I'm talking about desires.

"Gays and leftists" definitely want to "destroy their culture" and "flood them with Muslims".

If we would hold a poll, "should Poland accept whole lot of refugees from Middle East?", what response would you expect from "gays and leftists"? I would suspect they'll be at least 60% pro "Poles should definitely accept as much refugees as humanely possible".

Also met quite a few leftist/ultraliberal guys who not only thought that countries and nationalities were obsolete concepts, but were ready to implement that world-view at once.