Listen, as someone who works in a field that regularly reports child abuse, it’s on the person who witnessed the abuse, or who the child divulged the abuse to, to report to social services. That would be McQueary.
At least that’s the way it should be, but PA operated under an old statute back then that the person who witnessed it reports it to the top administrator who reports it to social services. That would have been Spanier, which is why Paterno sent McQueary to him. There’s still a problem though—without knowing the ID of the kid, without having a kid to interview, and without evidence (i.e. marks, testimony of the victim, etc), they won’t take the case. So even if every single one of them, including McQueary, contacted social services, they wouldn’t haven taken this particular case.
Now, you always report. Even if it’s third-person hearsay you know they won’t take, or you don’t even have the identity of a victim. Sure, it’s predictable—you call, give them the info, and they say they won’t take it. But you still do it because you’re covered. Imagine how different it all would have gone if Spanier, on the stand, testified to having reported to CYS and they didn’t take it.