if its an option (true/false) as you can spend a lot of time processing gp etc which doesnt require you  to move around ,

PlayerRankings does not track or modify time. The dependent plugins (Playtime Tracker, ConnectionDB) handle those components and you would need to request that feature from the authors although I am quite certain that Playtime Tracker already provides that ability to not count afk time.

Playertracker have the option, but doen't work with player ranking, I had to put a afk kick plugin...