There's a big difference between conflict and the occasional service outage due to a cell tower being collateralled, and the government coming in and shutting down the operation of the business. There are (or at least were) microwave dishes to the switches that chokepoint a lot of cell service. In case you don't believe it can be done, if the government has the desire: Taliban shut down cell phone service from dusk to dawn.
We shall see, won’t we? If 90% of cell phones in a confict area are shut down, it takes away the phone service to the 99% of the population that is not rioting, causing more hardship. But 10%, who have phones on different exchanges, will still have service. That will be enough for the flash mobs.