Being able to shoot them down is good. But it is also necessary to differentiate. Shooting down bombardment satellites isn't the same as shooting down a spy satellite. The one provides an imminent threat, the other one doesn't. The orbital layer is going to stay pretty much empty if shooting satellites down, was cheaper than to bring them up. Thats why you can assign a cost to take down a satellite, place the harmless satellites on the one side, and the harmful satellites on the other side of that barrier. One group is worth to be shot down (and you should do so anyways, since they are dangerous), the other one isn't worth the effort.