I think it is a slightly larger risk than that because a joker could plant say an arduino with a bluetooth shield, or an old throwaway android phone somewhere a

I think it is a slightly larger risk than that because a joker could plant say an arduino with a bluetooth shield, or an old throwaway android phone somewhere and script a program of actions, or maybe use a bluetooth antena (do those exist?) Also, is this a specifically short range bluetooth? Because my old junky bluetooth headset still gets enough range to reach my phone in my room from the bathroom nearby. I agree with you that the short range makes the threat much smaller, but it doesn't completely eliminate it.