This has nothing to do with Terrorists, this has everything to do with high profit legitimate customers being forced onto US owned aircraft.
By taking out the hubs for competing airlines, these passengers will instead use a flight where they CAN use their devices, and these hubs are where US owned aircraft have better access.
For example the USA has about 38 "Hubs" where various companies fly through , so instead of a direct flight you have a stop over in one of these hubs. It concentrates passengers and allows a greater efficiency and profit. If you ruin a hub (such as not allowing portable devices in the cabin) high profit customers will use an alternative airline.
This is all about removing competition for high paying customers in the from/to USA flight sector.