Well, BluexDreams, you are almost right
The feature present in Plus! allows the user to change their status after a period of inactivity. However, there is an advantage of the way I posted: my way will work right on sign in, not after a period of time.
I agree though, that, seeing as he/she would like to always have his/her status set to Away, a combination of both the plug-in and that option, could be useful
/ 
