The very first time that happens, maybe he could have thought it was a network error.

But Aaron kept on evading every single countermeasure MIT was putting in his place. By the time you get to going into a wiring closet, you have well passed the point where you know you are no longer welcome on the network.

The law cares very little about what tools you use, and they care a lot more about the actions you do and why you do them.

Aaron wasn't an idiot. He knew MIT was trying to keep him off. It wasn't just a network error.