I think the suicide is beside the point here. The undoing was getting busted and having the book thrown at him.
"His jury trial was looming when Swartz took his own life in January, 2013.
MIT faced a firestorm of criticism in the wake of Swartz’s suicide. Critics, including Swartz’s family and prominent MIT alumni, said the institution betrayed its own principles by not advocating for less harsh treatment of Swartz."
I can't see how "undid" would point to anything other than his "not being here". His presence being undone. His life being undone. If he would have been incarcerated for life, I don't think Kevin would use the word "undid". He would print "Free Aaron" stickers, and getting the word out that this fight should not be over.
I've actually never seen this wording being used ever, so for me it seemed quite similar to "doing someone". Yes that also means "screwing someone over" but for me, when reading "undid" a quote from the movie Trainspotting came to mind.
"Begbie didn't do drugs either. He just did people" and that involved a knife usually.
/edit: Considering the dictionary's definition I will hereby withdraw my suspect of any intent by the author to suggest that another person or entity was responsible for Aaron's death :)