Why rush him back? Seems pointless in this crap season. And it would sure seem hasty if it is a high ankle sprain. What's the point?
Furthermore, after tonight's fiasco, why not give our guy Eli a chance to play his last game at home, with a crowd that will be cheering for him?
You run the risk of destroying his confidence and possibly making the injury worse. Let him heal and come out fresh in 2020.
Use the next 3 games to see if Gallman deserves to be the #2, and to give him the experience he hasn't gotten so far.