I can't see a reason to kick out afk players. The game is looking empty enough already. Keep the mannequins in the windows. It doesn't impact server performance.

They should just make them perform progressively more embarrassing/absurd emotes as time goes by. It would be funny to come back from afk to see your character surrounded by a wall of beer cans, duct-taped to a pole, or digging a hole to nowhere.