I must say I have a hard time imagining how you are holding the camera, I never come close to that part of the bottom on my L1. My finger tips are around the lens, my palm under the body, my right hand on top. The way I hold all cameras, so I can manipulate the focus or zoom.
Bear in mind that in your photo you are using the large kit lens that came with the camera so your hand is placed well forward to steady it. I often use (smaller) third party prime lenses with adapters. I do hold the camera in a similar position to that in your photo but especially with smaller lenses it naturally occurs that the palm of my hand is further back towards my body - cradling the base plate of the camera to steady it. In this position my index finger and thumb are holding the lens (to turn it for focus) and my pinkie finger rests on the underside of the camera body, (steadying it) almost exactly on the battery door latch. As this has no real resistance (spring) holding it shut the slightest inadvertent movement can cause the door to flip open. A further slight movement (easily done when concentrating on picture taking) can then un catch the battery lock causing the battery to eject.
I suppose you could say its a bit like the old doctor joke ......."Doctor, it hurts when I do THIS!" to which the doctors replies "Well don't do THAT!" But its still a slight design flaw in the camera. Minor I grant you but it has happened often enough to convince me that it is not just me, its the way the camera has been designed.