I'd just rest him till this is long over in the barn. He'll get all the exercise he needs at pasture. If either of them are weak and getting abused at pasture I'd fight to get them seperated from the group. If she doesn't have more turnout options then I think it's time she made more options. She's gonna have sick and recovering horses there for awhile. Temporary electric fencing is not that hard to put up. I'd keep him out of bad weather and baby them both for a time.