What function would that serve, exactly? IMO, if a user asks to be logged out he/she should be taken to a page that says &you have been logged out&. Taking them to their web site would more than likely produce unneeded confusion.
This function doesn't work anyway. I would remove it since the user *thinks* is logged out but in reality reloading the page (or re-entering the URL) will directly lead to the CP.
I would suggest following text instead of &logout&: &If you are in an internet cafe and don't want others to mess up with your site, quit the browser (close all its windows) and if it doesn't work, shut down the machine&.