Okay. I finally uncovered the article online, Jens:
http://www.sussex.ac.uk/linguistics/documents/q1025_lecture_8.pdf
"In Kabardian (Caucasus) (8) the antipassive indicates uncompleted or
habitual activity, or a non-specific patient. Both of these phenomena
correspond to the concept less than prototypically transitive."
I think that is a pretty clear statement. So, as I said, claiming that
the *-e found at the end of IE perfects once functioned as an
"antipassive" of all things would produce the exact opposite effect of
what we're after, which is a _completed_ activity. It also is completely
contrary to an accusative-style language to have an antipassive. The
underlying stage of IE shows a bare nominative and an animate accusative
marked with *-m. No ergative case, no absolutive case.
= gLeN