the thing is, there certainly are incidents of modern slavery in the software supply chain. I would absolutely bet on it.

all of the big tech companies outsource a lot of their engineering work to subcontractors, and the US employer-sponsored visa system has been designed in a way, where, unfortunately, the fact that an employer sponsors an employee's visa could be held over their head coercively.

so the scenario outlined in the GNU Emacs debate isn't even that far away from something realistic and still unethical...