I suspect Paterno was such a powerful intimidating figure and getting up their in age that no one wanted to confront the guy and put their career in jeopardy I suspect the coaching staff were concerned about their career path that they knew enough about Paterno to not rock the boat and hope for the best. I am just guessing their was a deep denial factor too that someone from his era like to be exist in.
People said much the same thing about Pope John Paul II with regard to the homosexual invasion of the seminaries since the 60s and his 27-year papacy in which it flourished under his nose. He is said to have dismissed wanting to hear anything about it from senior advisors because during the Nazi era in the Poland of his youth, false accusations of homosexuality were enough for Communist overlords to ruin the careers of local officials and have them carted off to the extermination camps. Yet I hear no one on FR calling for him to have been jailed.
I lived in an Italian Catholic parish in Pennsylvania for a long time, and enjoyed the neighborly company of the many devout Catholic family men and grandfathers there. Given Paterno's age, I can completely understand his inability to fully grasp what he was dealing with. It is an imagery so disgusting and foul that he may not even have wanted to spend an unnecessary millisecond on it.