From the linked Cory Doctorow eulogy:

This morning, a lot of people are speculating that Aaron killed himself because he was worried about doing time. That might be so. Imprisonment is one of my most visceral terrors, and it's at least credible that fear of losing his liberty, of being subjected to violence (and perhaps sexual violence) in prison, was what drove Aaron to take this step. But Aaron was also a person who'd had problems with depression for many years.

A depressed 26-year-old faced a significant probability of spending decades in a small steel cage in which he would face a high likelihood of being repeatedly raped.