The answer is why the fascists turned "globalism" into a dogwhistle. It's quite simple: You don't do that. You liberate those workers too, through whatever means work.
Socialism is by necessity a globalist ideology. It doesn't do your commune any real good if you buy all your necessities from a slave labor camp.
An injury to one is an injury to all, workers of the world unite, etc etc etc. You must reject the principles of nationalism, or at least principles of non-interference, or you end up merely outsourcing the exploitation.