I agree most of the trial made little sense. Learning that Malcolm Meryln manipulated it did make sense than. There was some lazy writing there no doubt. But I suspect the DA was completely under his influence. It was a show trial to get revenge on Moria by tainting her public reputation. But also done so she did get away with her role in the undertaking. So the jury was given responsibility for giving her a pass.
Not clear on what Malcolm's motivation in helping her at all though? They secretly had a daughter. Thea is never going to accept him. He must have a larger agenda.