Whether the Commies believe this or not, it's a complete ludicrous theory.
How about all those Latin American countries, who have a working class that is ANYTHING but content? How well has Marxist ideology worked there?
And don't tell me "it's the forces of reaction and counter-revolution." The Marxists have terrorized and killed far more of the abject poor in those nations where they operate than the government forces have, because the Marxists KNOW they have to cow the populace to even get them to cooperate. It's not as if they're eagerly falling in line for the Long March here.
Now, I'm not saying that "open borders" is okey-dokey, not by a long shot. But I think that if the radical Left want illegal immigrants here, it is for VOTE FRAUD, not to foment this silly revolution that's now about seventy years late.
If we cut off social spending and the welfare checks and food stamps didn't get sent, we'd have some serious rioting and burning in no time.