its likely he was using it in a similar manner to why he was using 'thymosin' at Essendon, to negate the immunity reducing affects of heavy training. Or is it possible he was using TB4 to help heal the fracture but calling it thymomodulin. Everyone seems to think that was the case at Essendon
It'd be unusual for him to believe that an immunity booster is the cornerstone of their program though, wouldn't it?