I know from reading Burnett's book about the first Survivor that Tribal Council is a very long experience. There's much more footage there than they wind up showing on TV, and there's quite a bit of production overhead involved with pulling the whole thing together, as well. Jeff may very well have time to review the footage, but he's still making his best guess at the time as to what votes will ultimately be shown on TV.
I liked the good ol' S1 days when pretty much every vote was shown. Since there was really only one alliance, it was dramatically "safe" to reveal almost everyone's comments.