I highly doubt they were just going to let him waltz in there and rejoin E&D considering the responding officers first suspected he was one of the gunmen. Even after they no longer suspected him, there was no way he was getting into that building. To much of a liability. But IF he had somehow managed to sweet talk his way into the school, I'm sure finding Eric and Dylan wouldn't have been very hard. He would have just followed the sound of gunfire and exploding crickets. Yet I honestly feel that Eric and Dylan were going to die that day no matter what. I don't think they could have been talked down. They had already went to far and wasn't going to be taken alive. I truly think that no one would have been able to stop them, not even their parents.