You guys who are saying that OnStar is a optional service- it is.
But remember that the hardware is still there if you pay for the service or not. When you call up to tell them you want to pay for OnStar, who do you think turns it on? The same people who put it in the car in the first place. So, if your paying for it or not, if they want to turn it on and use it for whatever, they will.
Besides, no GM car lasts long in a pursuit or any hard use.