You are nerding out, I get it. But sometimes you gotta take off the “nerding out” hat before sharing an idea :)
But this is not necessarily a good thing. Labor participation of an enslaved group is surely higher and they work more hours per day...
Nor is it clear that other ethical practices outgrow societies that don't practice those ethics, e.g. China (and many other examples) and democracy.
Nor would you want to entrench a non-ethical viewpoint when it comes to nuclear warfare ( first strike / nonproliferation) / climate change.
This is commonly the flaw with Arab nations' use of their workforce of women. They are all working a lot of the time. It's just a huge waste of what they're capable of.
Slavery is similar. You just flatten everyone into unskilled labour. You lose. People will better fall on to the curve where they can participate the best in a free society than a slave society.
This sounds likely to fuck people up in the head and also to hurt your relationship, so I wouldn't do it myself but it is interesting to think about. The ends don't justify the means.
Slave labor can be more "effective" than workers with rights.
I'd rather humanity survive through slavery than be extinct through freedom, but I don't think I need to make that choice since I think free people self-organize into more resilient societies so long as they do not assume too much load of taking care of the non-adapted.
If the manner of their oppression is ethnic, then encourage that. If it's gender-based, then encourage that.
You can do this at the whole society level: for instance, no society that underemploys some large fraction of its populace will effectively compete against an equivalent one with efficient workplace participation.
So you can then blame them for all sorts of things. Guilt trip the Arabian nations for low participation of women, the Mississippis of America for low black participation. They'll double down and not correct. Then you beat them by just being better at using your people.
Sadly the article only hypothesizes this and doesn't talk about concrete evidence for the entrenching effect but one can hope.