In addition, we don't even know how much details Curley know, let alone Joe. For all we know, they could have had the impression that Jerry had done something along the lines of breaking a kid's nose from throwing too hard in a dodgeball game.
Even if you look at what actually happened it was, contrary to popular belief, a very benign incident. The boy continued to remain friends with Sandusky for 13 more years and alleged no further incidents. He sent Jerry texts as a 23 year old heterosexual man in 2009 wishing him a Happy Fathers Day and also saying he thanks God that Jerry has been placed in his life. He had dinner with the Sandusky's even after the March 31 Sara Ganim article came out leaking the investigation. Even after the November arrest, in January 2012, he told another accuser that he still doubted whether Sandusky was even guilty, and felt his Mom was putting pressure on him. If you read V6's testimony, it actually seems to help the defense rather than the prosecution.