McQueary is clearly reponsible for doing something. BUT...if he did as has been reported and went to Paterno, that's where the blame shifts.
Paterno should have said "Ok, son. Let's go. We have to take care of this. Don't worry, I've got your back"... gotten into the car with him and gone to the police...Sandusky's house...or at least the AD. That's what Joe Paterno "The myth" would have done...the right thing. Instead...the coverup began.
After that, McQueary is screwed. If he goes to the cops on his own... his life is literally in danger. One only need look at what went on Wednesday night in State College to know that's not an exageration.
That doesn't aleviate him of responsiblity...but it certainly begs the question..Why didn't he speak up? What was he afraid of? If he was truly brought up in this "culture of integrity and morality" that is Penn St... why would he not act accordingly. There's a good reason, and it's more than just "he's a P O S".
And that's why Paterno is ultimately to blame.