Hey, I agree that under most conditions if a phone can connect to make a call that it also probably can get and even transmit a GPS fix. But if they (Dawson County) couldn't access the GPS data on the emergency services side (which isn't always possible with old technology or in remote areas), or if the wireless carrier couldn't access location data (and they might only know which tower his phone pinged which would only give them a radius if there weren't two or three of the same carriers towers "visible"), or if he didn't know how to use his phone's apps to access GPS coordinates and then verbally communicate the GPS coordinates to emergency services, they (911) just simply wouldn't have GPS coordinates. There are also legal/privacy issues regarding this stuff, but they are off-topic.
Remember that according to reports, they only had a idea of his general location at a certain point of time (the call and then the later ping), likely estimated from his start point, anticipated route, and a tower location and it's effective coverage area due to terrain. But his phone went off line/dead after they were able to ping it the one time after the actual voice call. They (911) never reported having a GPS fix from his phone - only a general area location, but even if they did, if he was moving it was stale info by the time they got resources out. We just don't have the details. He lived in Eden, NC approx 300 miles from Amicalola Falls. When GPS receivers are moved large distances, they often need updated almanac and ephemeral data in order to resolve a fix. So, there is also the possible scenario that he had no data service or access to an aGPS server because he was roaming or had a limited data plan of some sort, and/or never turned his phone on until after he was lost and placed the call, resulting in GPS data not being able to be resolved - it could take quite some time for his phone to resolve a GPS fix if the almanac and ephemeral data had to be updated via satellite data speeds (and I quite honestly don't even know if all phone GPS systems will download using that method, I only assume that they do).