So he could have gone for trial, and serve his 2-3 year sentence (if convicted), probably get out early for good behavior, and keep his sacred honor. And it still would have been far better than hanging himself.
Why assume his sentence would have been 2-3 years? The prosecutors clearly wanted to make an example of him. He could have wound up with a 10 year sentence, or even the full 35 years. There is also no guarantee that he would be let out early for good behavior.
It's not just the sentence itself. Defending his case was ruining his finances. Once out of prison he would have faced numerous hurdles, which would become more severe if his sentence were longer.
This is not to say that suicide was the right choice. Rather it is to point out that we are not talking about a slap on the wrists; the prosecutor was going for his throat. Any rational person would be scared in that situation.
Because no less an authority than Jennifer Granick said [1] that the conceivable range of a sentence would be from 15-21 months (though she said it could go higher, so I rounded up to 2-3 years), and she is decidedly on Aaron's side on this. In fact she ended her discussion of sentencing with "But Aaron could easily have come out to over a year in his guideline calculation.". Either way the sentence is in the end not up to the prosecutors, whether they wanted to "make an example of him" or not.
Now is a year is an easy sentence? Probably not, but it's certainly not a very hard sentence. Either way according to Dr. Lessig the sticking point for Aaron wasn't the length of the sentence, it was the 'felon' label.
All the other hurdles you've mentioned, all of them, are surmounted all the time by much lesser men than Aaron. Sometimes I think that Aaron might have actually started to believe the type of crap that gets slung around here on HN about how being a felon ends your life, and I wonder if that had any influence...