there are 3, one in the booth, one on each sideline.
the protocol demands players showing motor instability, to be taken directly to the sideline doc, unless they need to go to the hospital. the Fins intentionally violated the concussion protocol by rushing Tua to the locker room. this bought them extra time (as much as 5-15 minutes) for Tua to clear his head before seeing the neurologists.
the fins then took the decision out of the UNC's hands by having their doctor claim it was a back injury. With Tua passing the concussion test, and the team doctor claiming it was a back injury, the UNC no longer had the power to keep Tua out of the game, and the dolphins team doctor now had the power to make the call.
I believe this was entirely intentional. This wasn't just about the Bills, the Dolphins had a Thursday night game too. had Tua been ruled out of the bills game with a concussion he NEVER would have got out of the NFL concussion protocol before the Thursday game. It was vital for everyone involved to continue the back injury story after the game. had the story changed, Tua would have been ruled out of the Bengals game immediately.
So this is how we got here.