"But the total abandonment by the party establishment of their sitting Senator and 2000 Vice Presidential candidate is AOK?"
That's what primaries are for. It was obvious the establishment wanted Lamont for one reason. That was his anti-war stance and they wanted to ride his coattails.
Once it be known that it wouldn't fly, they realized that Lieberman is going vote lib anyway except on the war, they may have a winning position on Iraq without Lieberan, so might as well throw Lamont to the wolves.
He served his purpose.