The typical ICM failure is that the engine will work fine for several miles then suddenly stall completely dead and crank but not start. After a few minutes to cool off it can be re-started. Testing during the time that it won't start reveals there is no spark.
If the car does this it's very likely the ICM. If it does something else you should check further.
The coil is prone to blow out and stay dead. A coil bad in this way will make small sparks to a grounded test wire with the cap off, but they aren't hot enough to fire the engine. Firing into an open circuit (bad spark wires or spark wire removed while running) is a lot of stress on the coil.
That is exactly what is happening. He drives for a couple of miles, the engine stalls and after pulling over to the side of the road, it cranks but won't start. After a few minutes, it restarts and then doesn't do it again for the rest of the trip. That is why we think it is the ignition control module.
He was thinking if he should replace the ignition coil while we are replacing the module.