For someone of Aaron's talent and reputation there is no reason that he could not have gotten past a felony conviction and lived a successful life.
I can only interpret Lessig's post:
"...the question this government needs to answer is why it was so necessary that Aaron Swartz be labeled a “felon.” For in the 18 months of negotiations, that was what he was not willing to accept..."
I don't know what the government actually offered, but it doesn't seem unreasonable that Aaron would have been able to get a deal with a relatively light sentence, maybe just probation. It sounds from Lessig's post like his hangup was that he wasn't willing to accept a felony conviction. I hope that's not the case because even with a felony record he most likely would have lived a long and successful life.
Being sentenced and getting a record for doing something you feel is right is not something everybody takes equally lightly. Personally I couldn't care less but I can see how someone with stronger principles would react much stronger to this.
It was not a real option. He had run out of money for an expensive, complex case. He was sure to lose.