I would rather firmly disagree with you, youre doing a greater injustice to him by ignoring how the articles alleged to be distributed were part of his long held beliefs and civic activism. Attributing this solely to "not knowing how to deal with internet crimes" doesn't really fit either - the Paypal 14, a cyber bullying case, the Morris worm, etc were all prior cases using the same act as a basis to charge him.

Let's be clear - he was a staunch and long term supporter of open access to information long before the incident at MIT. PACER is a good example of that, which had no charges brought against him.

In terms of the prosecution, yes, that was a decision by the Mass AG. That decision would not appear to have anything to do with "not knowing", and more to do with seeking to continue an overly broad interpretation of the computer fraud and abuse act. An interpretation that had been challenged by legal experts for years.

Now into the specifics here - the Mass AG based the prosecution around Swartz having an intent to distribute the materials. This is the part that has to do with his beliefs. His previous public statements regarding open access to information were part of this intent to distribute alleged by the Mass AG. So yes, his beliefs absolutely played a role in his prosecution (see the Guerilla Open Access Manifesto by Swartz)

Why it was such a harsh approach was based around, as mentioned above, the Mass AG looking to use this as an example of how others could be prosecuted, to push the limits of how the Computer Fraud and Abuse Act could be applied, opening up more options for the AG to be "tough on crime" (Carmen Ortiz, an Obama appointee who resigned when Trump was coming in).

To note, Carmen Ortiz has been accused by judges of stretching evidence, providing gross exaggerations of events, having "unusual" prosecutions. She oversaw the arrest of someone who kinda sorta looked like a wanted suspect, she agreed in pleas to lesser sentences and leniency but would then seek harsh penalties, tried to take motel via civil forfeiture despite the owner not having been involved/identified as part of/charged with any crimes.

TL;DR:

His beliefs absolutely played a role, and the US AG in Mass, Carmen Ortiz, often went waaayyyy beyond to get the harshest punishments possible.

So, I firmly disagree with your statement.

Edit: Cleaned up a sentence up top to be more clear. The Mass AG would allege intent to distribute due to his beliefs, though he had not actually distributed them.