Essentially he was exploiting a vulnerability in JSTOR to mass download court documents, what if he was downloading credit cards instead? Or some sort of corporate secrets?
(Sure, credit cards and court documents are very very different. But the act here is the crime, not what he gains from it)
He was downloading academic articles, not court documents. You're mixing up the JSTOR download and the time he pulled down PACER documents. He did have legitimate access to the JSTOR documents, but was bypassing rate limiting. In the process, he did do some things that were illegal, but nothing that honestly justified the Feds charging him with CFAA or wire fraud charges filed, nor anything that justified a felony conviction. What he was doing wasn't the sort of crime those laws were written to address and that they were intended to stop. The Feds. abused the ambiguities in poorly written laws to charge him.
What if he was raping women? Or committing genocide?
> But the act here is the crime, not what he gains from it
Downloading scientific journals is not the same "act" as committing credit card fraud. It is an outrageous defect in the law that it doesn't adequately distinguish them.
Swartz had previously downloaded court documents from a service called PACER. An FBI investigation was opened, but closed with no charges being filed; he was not prosecuted for that.