Recovery's a challenge. Different for everyone. My one big fall on a bike was relatively injury free. A bit of road rash, but that was it.
My worst injury was from over-doing it with a variety of sports, which all conspired one morning to fry a handful-sized chunk of muscles on a leg. Took a long time (years) to fully recover to be capable of swimming, running, cycling again, to the point I wasn't worried about the leg collapsing or re-injuring.
Kudos to your friend for getting this far. And Kudos to you for assisting in ensuring the friend doesn't push things too soon.