The goal is to reduce spam, and reduce the human intervention needed to reduce spam.
Right. I support the secretariat's efforts to reduce spam and associated management effort on the IETF lists. Personally, I have a good experience with SpamAssissin, so to me the technical arrangement looks quite reasonable.
As for the rest, lets all remember that there may be no fast, perfect, and inexpensive solutions. It may not be reasonable to require that the false positive rate is zero. We certainly can't replace spam detecting tools with e-mail signatures and have it operational tomorrow. And if the IETF has unused cash, there may be better uses for it than paying for spam detection software.
--Jari