I think Eliezer can't be reasonably accused of trying to redefine "rationality" and the problem is on the part of the Metafilter commenter. It seems easy enough to fix though. Just point them to http://en.wikipedia.org/wiki/Rationality or http://books.google.com/books?id=PBftMFyTCR0C&lpg=PA3&dq=rationality&pg=PA3#v=onepage&q&f=false
Good call. There being an Oxford Handbook of Rationality with a chapter on Bayesianism seems to show that the term is acquiring new connotations on a bit wider scope than just on LW.
It seems we have agreed that open threads will continue but that they will go in the Discussion section, so here's this month's thread.