You said that the Officers were facing each other. Could they have been watching each others backs?
I have never heard of anyone mowing down a row of police bikes... have any of you?.... Besides the movies.
Honestly most of you do NOT have more situational awareness than the average cop. Well the average street cop that is. Where most people work at gaining S/A, with street cops it's second nature. It becomes ingrained after a very few months on patrol.
I agree that complacency may get you killed. In fact I've known a few officers who allowed their complacency to cause their death. But it's usually more complicated than that, or maybe even more simple than that.
Since the officers were inside the resturant, and the bikes were parked outside... I guess they do have a way of getting off of them when they are parked so close together.