If I am the approaching vehicle and someone legally on the road ahead of me is travelling slower than me (bicycle or pedestrians included) and I run into or over the one in front of me it is almost assured that I am at fault. Bicyclists use this to their advantage all the time.
I have investigated many boating accidents and in every case the boat that was approaching from behind and collided with a watercraft going the same direction the overtaking boat operator was at fault.
I haven't read this whole discussion but I'm assuming the old woman didn't jump out in front of the bicycle when she turned to look. Sounds as if the bicycle was going to barely miss her at best if she hadn't turned to look.
