I think you're not parsing his sentence the way he intended it to be read "alienated due to fear of immigration" vs "alienated due to immigration". Of course, the EU also have their own share of immigration, at least in the past few years. But even with a whopping 15% of their residents being foreign-born, often the remaining 85% look the same, sound the same, are members or atheist ex-members of the same church, etc