From the aforementioned Terminal window:
mv ~/Library/Application\ Support/Tremulous/base/autogen.cfg ~
This will move the autogen.cfg file from your library to your home directory, where Tremulous will ignore it. If that works, then you can open that file with a text editor to see what binds you had set and what not, and add them to the newly-created file since the game will make a new one when you next quit.
Alternatively, if you're feeling frisky and/or have a lot of binds you don't want to lose, edit that file with your favorite text editor and remove the offending line (probably the one you mentioned, or something near it). But if the 'mv' command doesn't work, you can always move the file back later and try that (with "mv ~/autogen.cfg ~/Library/Application\ Support/Tremulous/base/")