Why was the terminology changed? It's written as slave throughout my MFM books.
Lots of people didn't like the baggage around the word slave. The newer channels changed it, and the change has pretty much stuck.
It's not the only bit of terminology that's changed. The neutral goal got changed to Flow, for example, and the Sexual Center got changed. Among others.
The best thing to do is to dig a bit: the ordinal inspirational goal is still just as ordinal and just as inspirational, whether you call it Slave, Server or Ruler From Behind The Throne. (or Tender of Children, which I've also seen.)