I've gone through the back thing. Yeah, sedentary is not the answer. But you don't want to OVER stress whatever muscle that is pulled (& inflamed). Mine was a tiny one, when it went it felt like someone had shot me with a gun. I couldn't sit for more than 30min without a lot of pain, had to go back & forth all day from standing using laptop & sitting using it at work; even getting out of bed was not easy. I tried rest, then massage, then chiro, then Dr, which led to PT. PT was the only thing that worked. They have you do specific exercises to that muscle that is pulled (once they identify which one), and for me I think what helped most was the TENS unit sessions that they also do. TENS unit? It is a small device that sends electrical impulses to the muscle(s) where it is attached (they usually surround the area), think mini-electricusions. They tell you to let them ramp it up as strong as you can stand, and then you get that for about 15-20 minutes a session. It hurts a lot, but at the same time helps. You or I, we are getting that PT treatment 2 maybe 3 times a week, I'm sure Carr is getting it 2 maybe 3 times a day.
So I would agree with sitting out practices. That is an environment where he may push that muscle "over the limit" on a play setting him back to starting point 0 on his recovery. But at the same time, I doubt he is laying in bed in the dorm being sedentary, he is doing various stretches and other treatments probably multiple times a day, to get that muscle back to where it needs to be.
(I too, am not a Dr, just a statistician who does work with doctors, but I have had a similar condition)