Practically the "Away From Keyboard" option only highlights your name and makes it red. The only way someone knows if your "Away From Keyboard" is if he is in the same Tower, O'Club, Hangar, Range, or VOX and on the same team as the player who is "Away From Keyboard". How about HTC makes a new option that if you press "Away From Keyboard", it would automatically reply to "Private Messages" sent to the user who is "Away From Keyboard" with a message such as:
This user is Away From Keyboard.
That way not only is the user informed that you are unavailable, the user won't be shouting at you thinking that you are un-polite. Just a suggestion.