Apples and oranges. Joe didn't cheat, he didn't even technically break the law and reported it to his Supervisor.
The Grand Jury indictment indicated that there were was a PA or local law on the books that required educators and coaches to report abuse to the authorities. While he did report it to the AD, it's a very murky area that wouldn't bode well for Joe Pa if they did take him to court, as Joe Pa did not follow-up on this issue and inform the 'proper' authorities for years after it happened.
That's a chance for every day that Joe Pa could have went to the AD and said 'what came out of that boy in the shower situation', and if he wasn't given a straight answer, he goes to Spanier, and then the cops.
The only reason that Joe Pa is likely escaping prosecution here is because he cooperated with authorities and the Prosecuting Attorneys, and because the easy kills/low hanging fruit are Sandusky and those they accused of perjury. Plus, if this situiation is a media circus now, imagine what it would be if Joe Pa were charged with perjury or another charge implicating his complicity in this matter, intentional or otherwise.
No, this is more than hindsight--this is willful neglect, and any reasonable, rational person that hears reports of a 10 year old boy being sodomized in a locker room shower you're responsible for would follow-up and ensure that the *proper* authorities (read: police, not AD or Chancellor) were notified.