I just really have to ask why conducting a trial is an injustice.
One word: intimidation. Trials aren't free, short, stress-free processes. If one happens that threatens the person on it with prison and / or high fines, and the case is on some pretty shaky legs from the get go, the supposed injured party going on record that they don't even care, then yes it's an injustice. Now this person is forced to spend a lot of his time and money on this process; time and money nobody's going to give back to him. Not to mention stress and impact to general health. That's assuming the person isn't suffering from depression and won't off himself before the process even begins, which is what happened here. So yes, trials aren't the same as convictions, but they're also not happy memories for the people involved and shouldn't happen lightly. Or in short, the legal system shouldn't be used as a form of intimidation / legal racket. Unfortunately, any system is only as good as the people it's made of.
A good mental exercise is to picture yourself accused of something that you either didn't do or was just horribly (possibly intentionally) misinterpreted to serve someone else's interests. Are you going to be happy you'll get to have your day in court and exercise your rights to defend yourself, or are you going to be stressed and angry because for the next several months (years? depends on the case and where it's being processed) you will be spending time otherwise spent with your family / job / life in general on a legal process you're not guaranteed to win, and if you don't you're facing some jail time and / or high fines? Now add depression into the mix and you have a pretty good way to get someone to commit suicide before it even goes to trial.