A silly issue, distracting from real work
I don't think that anyone is directly offended by the words. Actual slavery was abolished in U.S. about 8 generations ago.
Instead they are being pseudo-offended on behalf of theorized other people.
Even while rolling my eyes, I wouldn't have a problem with getting rid of the terms if there were equivalent replacements. But in some contexts they are the simplest, clearest terms to use.
No doubt if we got rid of the terms, the replacements would end up with the same connotations and subsequently need to be replaced viz. the chain of euphemisms for bodily functions, each of which turns into a word not used in polite company a generation or two later.