I think "kyusha" is a lovely word. Some people tend to forget that Japanese is a building block language, and some people forget that "aikido" is a word O'Sensei made up out of building blocks. Some people seem to feel that only native Japanese people are allowed to do this.
I'd say that only people with a working knowledge of the language should do that. Since I don't have a working knowledge of the language, I don't do that. Sorry, but there is a right and a wrong to many things in life. That's just the way it is.
The word "mudansha" implies,to my mind, a state of "not having" as in, "I don't have rank because I don't have a dan grading";whereas the word "kyusha" implies to me a state of "having" as in " I have a ranking of 2nd kyu". Coming from a negatively-oriented person, I'd rather be though of as a "have" than a "have not".
I guess I'm just surprised that anyone would have to make up a word that doesn't exist to feel better about something that doesn't make any difference anyway. I've been tossed by people with literally no rank as well as people with rank. Women as well as men. Small people as well as big...you get the idea.
Anyhoo, butting out.