Regular Joe should have pushed MM to contact the authorities in addition to taking the matter to Curley. He knew a sexual event occurred between a boy and a mature male... clearly his actions failed.
His actions clearly didn't work out as he would have hoped, surely. With the benefit of hindsight......... and all that.
Joe correctly got Mike in touch with the people at the school who's responsibility it was to evaluate the situation. Plain and simple. Could he have pushed Mike to contact authorities? Sure. In fact, he did get him in touch with the man that was in effect the chief of police. I suppose Joe could have strapped him into his car seat and driven him to the police station. But the fact of the matter is that Mike McQueary was a 27 year old man. Not a little kid. A fully grown man. At any point in this whole ordeal he was free to contact authorities on his own. He chose not to. In fact, he never did. He waited for police to come to him ten years later.
There were many failures in this ordeal. As a person who works in this field, I can tell you that Joe's failure is not in his actions. He did exactly as he should have done. Exactly. His greatest failure was in trusting those he handed it over to, to handle it properly. And I suppose another failure was in trusting Mike, whom I don't put much trust in.