It's an interesting way to demonstrate the density of the satellites- they're not hiding the number or duration of images, so you can get a fuzzy intuition for how likely you are to catch them in a given image.
Except you're not actually demonstrating the density. That could have been one satellite if you exposed long enough.
It's like taking a picture of the one car every day driving on some empty road and then coadding them and claiming you're demonstrating density of traffic.
