Since you seem to be in the know, do you think his current situation actually needed the surgery? As far as I can tell the issue was that his shoulder dislocated easier than it should, but then again this only happened if he fell on that side, and also apart from that it didn't seem to cause him other issues, that we know of. Some would even say it's better to dislocate a shoulder than break your collarbone, which usually happens in these type of falls.
Only his doctor could confirm what was done. A chronic dislocating shoulder is fairly painful: think of an icepick being driven into the joint. Usually that requires rotator-cuff surgery to repair shredded or extended ligaments that would stabilize and define the joint's motion. That can be a 6 month ordeal to rehab.
In that area all of the nerves that serve your hand, wrist elbow, etc run from spine and under your shoulder blade into the lower part of the joint. It can be dangerous to drive or ride if that joint displaces while active, which could have been the chronic problem. If a graft supplement was involved; it probably was to augment the glenoidal joint (where arm "head"/humerus contacts) because it no longer could resist some critical movement due to damage to the cuplike shape. Grafts can be a challenge as the tissue needs to be accepted. They may have taken bone/cartilage from another area on Primoz to minimize rejection of cadaver tissue replacement.
Collarbones are a piece of cake to manage IMO unless there is severe displacement that could penetrate the skin or damage other tissue. If not, you could easily race after breaking the collarbone. Just grit your teeth like Tyler Hamilton did to finish a GT. Displaced versions usually get a plate or rod alignment stabilization and will take a while to heal.
My conclusion is I'd rather have neither but a collarbone break general has much less long -term consequences. It wouldn't surprise me if his dislocation issues started with another sport as it is a rare consequence of crashing your bike.
Disclaimer: I'm not an orthopedic doctor. Old Labrat is more appropriate.