I think that "is not" statements can actually help one break free from th damaging effects of "isness". For example, let's say I've developed a habit of thinking & saying: "I
am a bad person." Not a very healthy habit. But, th statement, "I
am not a bad person," can help reverse th effects of th more damaging one, if I make an attempt to accept it. Of course,
I'm not a bad person!
I'm not anything; no one can "be" anything at all.
"I
am not a bad person," does not mean th same as, "I
am a good person." Th latter bonds us to a self-limiting identity, that of absolute "goodness." Th former breaks us out of a different self-limiting identity, that of absolute "badness."
Of course, "is not" statements can damage also. Take this sentence: "You're not one of us."
Anyway, whether th negative copula "counts" or not, I couldn't say, but I would suggest that it can fit with th spirit of E-Prime.
My 2 cents,
Andrew / Nodal Nim