An appeals court does not try a case on merit they rule on whether procedure was followed and to address the questions raised by the party presenting the appeal.
The only decision rendered here was to overturn a dismissal and allow the original court action to proceed. Obviously the two people arrested for defacing feel that their Freedom of speech was denied yet in order to prove that they will first have to admit they were knowingly breaking the law. I do not personally see any reason they should not have been allowed to chalk their words but the assertion that their arrest was motivated by the content of the message will need to be proven in court.
Currently this case is the legal equivalent of arguing that your ticket for running a stop sign is invalid because other people that did it last weekend only got a warning. If in fact it was selective prosecution I hope to see Justice done.