This is an interesting theory, but it falls apart upon contact with reality.

The vastly overwhelming majority of immigration barriers in the world keep people out of other countries, not keep people in them.

The motivation behind those barriers is, broadly speaking, in keeping out moochers and undesirables, not "Actively helping some country on the other side of the world repress its citizenry."

You'll be hard-pressed to find people who support strict immigration controls for the latter reason. You don't have to look hard to find supporters of them for the former reason.