Back on TOPIC!
I have decided to place an order for the locking mechanism. Even though it isn't the most secure setup, I've reasoned it does act as a deterrent, under "normal conditions". Let's face it, someone could just as well cut all the wires and take the camera, if they wanted to destroy evidence. So the lock doesn't prevent this from happening. What the lock does resolve is conveniently yanking out the power cord or claiming the power cord "came loose".
So if you take your car in to a mechanic, valet, etc and magically the power is cut, you're going to know it was intentional. Either through pressing the power button while the car is on or undoing the lock, pulling the cord, or ejecting the memory card. There's no "it happened on accident" excuse. Putting the proof on whomever to explain their actions, if something happens while the camera is "off". Which to me is worthwhile. It also ensures the power cord and all cords will not easily come loose.