That book confirms my suspicions. A lot of this was due to Paterno's age. He didn't know that male on male rape can happen and he wasn't diligent in these later years...
Many of the people who had come to admire Joe Paterno believed that, no matter his own legal role, he should have made sure the incident was reported to the police. 'But, to be honest, that's just not how Joe was in the last years,' said one of the people in his inner circle. 'He was not vigilant like he used to be. I think a younger Joe would've said to Tim after a few days, "Hey what's going on with that Sandusky thing? You guys get to the bottom of that? Let's make sure that's taken care of." But he didn't understand it. And he just wasn't as involved as he used to be,'" the book reads.
Posnanski notes that after Paterno's family convinced him to read the grand jury presentment outlining the charges against Sandusky and two other Penn State officials, the 85-year-old coach asked his son, Scott Paterno, "What is sodomy, anyway?"
It doesn't excuse it but it does explain how this could happen. As Paterno later admitted, "I wish I had done more", by that I'm sure he means reporting it to police. If he'd made that one phone call, this whole thing would have turned out differently for PSU.