If the authorities want to stop you from calling, they can
already tell the providers to block your IMEI. They can also track you as you move between towers, listen in to your phone calls if they want, and read your SMS messages. But seriously, the providers can
already "brick" your phone - otherwise, how do you think they shut off service when you stop paying your bills? How do you think they know to charge you for your long distance calls? And similarly, the police/NSA/CIA/FBI/whomever already has all of those abilities, simply by telling the phone company to give them whatever they want.
Enabling a kill switch is not really creating a new kill switch... It's simply giving you, the purchaser, the right to tell the phone company to block the IMEI using the same tools that law enforcement does now. It literally costs them nothing to allow, since it already exists, but, as noted in the Summary, will result in a huge drop in the number of re-purchased phones after theft/breakage... phones that are frequently re-purchased at full price, due to the multi-year contract lock-ins. This is all about money, not freedom.