I imagine this would be a relatively simple addition to the existing proxy's that are available and could be useful to secure a meeting area or party from unannouced intrusions etc.
If the proxys could be commanded to remain within a distance of 10m of when the command was issued but be placed on aggressive mode so they attack all enemies etc. That way if you held a party/meeting you could install your proxy just inside the buiding and provide a defensive wall. Correct positioning adds a little strategy into the mix, moves towards creating semi-safe zones in the hostile environments (could also be placed at the perimiter of certain hl areas etc) without tying up the player themsleve who probably wants to be involved in whatever event is taking place within?