Enslavement only matters if your level of productivity is still on roughly the same order of magnitude (as in, up to minus a few) of your masters. e.g. you are

Enslavement only matters if your level of productivity is still on roughly the same order of magnitude (as in, up to minus a few) of your masters. e.g. you are a cow, a jug of your cow milk is still worth a few dollars in human markets. That means it's still worth it to keep you around. If you're a mosquito OTOH... even enslavement is not worth it. It's eradication.