They are used for undergraduate pilot training, as well as RPA (drone) pilot training
More precisely, the RPA guys will be trained in the T-6 simulator.
Within the Air Force, training for drone pilots is divided into two parts. During the first phase, recruits spend around five months learning to fly a manned trainer airplane, working the flight simulator, and understanding the fundamentals of flying in classroom lectures. This phase is split between Pueblo,
That is a direct quote from a USAF site. It would appear, they get some actual stick time in the T-6 as well as simulator training. It makes sense, since UPT, for manned aircraft, is at Laughlin, Vance and Columbus, why would the USAF have real T-6s at Randolph, if RPA training did not include stick time in the actual T-6?