Thats the thing though: If the core part of your ethics argument is just using dehumanizing language to justify why it's ok to maintain the status quo then your argument is bad.
Comparing specifically to pro-slavery perspectives makes that easy to see because those arguments from slave owners did basically the exact same thing (and were completely wrong/misguided in hindsight).
>de"human"izing
Slave owners did it to people, not software. This comparison is just begging the question, as whether or not software is of moral weight comparable to humans is precisely what is at issue.