Calling someone isn't considered analogous to trespassing, while accessing someone's network is. I don't think that's a meaningless distinction at the technical level either. Calling someone is like issuing an HTTP GET on a public server. Putting a computer on their network is something quite different.
As for whether banning they MAC address conveys revocation of the license. The precise form of the communication is irrelevant, it's about whether it can be expected to get the message across in context. Do you think Aaron didn't know, after the various measures MIT took, that he was no longer welcome on the network? If he did know, then the message was conveyed.
You're basically attacking a straw man. You're acting like he was charged for trying to access the publicly-available MIT home page, getting a 404, and trying again with a different laptop to see if the problem was on his end. That's what would be analogous to your "calling someone who isn't answering then trying a different phone" example.
As for whether banning they MAC address conveys revocation of the license. The precise form of the communication is irrelevant, it's about whether it can be expected to get the message across in context. Do you think Aaron didn't know, after the various measures MIT took, that he was no longer welcome on the network? If he did know, then the message was conveyed.
You're basically attacking a straw man. You're acting like he was charged for trying to access the publicly-available MIT home page, getting a 404, and trying again with a different laptop to see if the problem was on his end. That's what would be analogous to your "calling someone who isn't answering then trying a different phone" example.