I watched a fair amount of the trial and I don't see how they could have found him guilty after seeing the prosecution present it's case. The defense raise the "beyond a reasonable doubt" argument very well. The prosecution had a horrible case to start with and did a horrible job, it really never should have gone to trial.
While I don't think he should have been there, that's not what the trial was about. None of others should have been there either, it wasn't about protesting that night it was about destruction.