Only a matter of time before a nefarious person discovers how to trigger the kill switch at their will. If this happens, Intel will immediately go out of business. They know they can't just blame the NSA. That's why Intel has every incentive to aggressively fight such orders.
The kill switch could be anything:
1. Some particular frequency that causes the CPU to malfunction deliberately. Just a 1 bit malfunction is enough. 2. Something delivered via an OS update patch.