McQueary is a very large intimidating person.
I can’t imagine why he would fail to physically intervene. He could have kicked the guys butt easily.
Look at how high the cover-up went. All the way up to President Spanier. Sandusky was a hero at PSU. The grad-student probably saw his future going down the drain. As it came to be, everyone covered up, they gave the grad-assistant an assistant coaching position and Sandusky was free to rape again and again and again and ....