The MIT network isn't "public." They let guests use it with proper registration. You ignore MIT's repeated attempts to lock him out and his working around their countermeasures each time, leading to more and more escalation. If he had just run his scraper exactly once and then stopped the first time he was kicked off, no one would have cared.

He also wasn't facing "multiple decades in prison." This has been debunked so many times it's getting exhausting, but once again I'll point out that his lawyer was not a complete hayseed and understood that, even if Aaron went to trial and was found guilty on every single count, he would face at most a few years in jail, and quite possibly no jail time at all.