Doesn' make it right, it's just what it is.
This is the point that many of us have been trying to make that I guess you overlooked.
It doesn't matter why he turned his head. It doesn't matter if 90% of people in the same situation have done the same thing (although I seriously doubt that statistic, if accurate in the first place, is applicable to people who have seen a grown man anally raping a child in an open shower room).
The main point is that it was wrong for them to have turned their heads and ignored it. Sure, point and laugh and call us Peter Parker, Arthur Curry, Clark Kent, or whatever else makes you giggle with glee. Point to ambiguous, uncited, and probably irrelevant surveys and say that, statistically speaking, we wouldn't do anything either.
But despite what you say, despite what the surveys say, and despite what has become the "norm" amongst companies and institutions like Penn State, I wouldn't stand for it. Especially not when directly confronted with recurring charges, reports, and suspicious activities.
If you can't see yourself intervening simply because the statistics dictate that you're likely not to, then that's your choice; it's not mine, and I don't see why it's ridiculous for me or anyone else to point out how wrong Joe Pa and a variety of people within Penn State are.