“slavers” “Peculiar institution” have unnecessary pejorative connotations, adding nothing to an historical discussion.
Both "slavers" and "Peculiar institution" are precise historical terms for the people and laws of the time.
There is no good reason -- none, zero, nada good reason -- to euphemize them today.
"Peculiar institution" wasn't a pejorative term used by Northerners or abolitionists.
It was a euphemism used by Southerners and slave owners, a way of talking about slavery without using the word "slavery."
"Peculiar" in this case didn't mean "weird" or "strange" but "unique to" or "exclusive to."