And in case the blogger named Miranda finds this (she replied to Prof. Shallit's post): No, civility, or alleged lack thereof, has nothing to do with Groothuis banning people. Groothuis routinely uses worse invective (ok, equally bad) towards others than I or other banned invididuals ever used against him. Only, since The Constructive Curmudgeon is his blog, he can capriciously ban people rather than accepting a challenge or engaging dissenters in debate. He is very good at finding the speck in other people's arguments while displaying an uncanny ability to ignore the log in his own.
As another blogger pointed out, calling someone a hypocrite, who is demonstrably in fact a hypocrite, is no more "invective" than calling a spade a spade.