His options are limited due to funds. Lawyers can be very expensive and if he is charged with a felony theft and also charged with failing to appear in court on that theft it can be a tough battle. I cannot provide you a magic formula that will help your son out of this predicament, but I would be happy to discuss with you the general things he needs to do while facing these charges.
Your son is being represented by an assistant public defender. These lawyers have dedicated their careers to representing indigent clients who are charged with crimes. I have known and worked with numerous assistant public defenders and I can tell you from personal experience that they are some of the most qualified and thoughtful attorneys who represent defendants in criminal court. However, they are grossly overworked.
Therefore the key for your son is to use his time with his lawyer effectively. You must understand that this attorney will not have time to return your calls immediately or respond to every written message they receive. Most public defenders are in court everyday and many cover more than one court. Your son's case will become a priority to them... but that will most likely happen on their schedule... not his.
I recommend that your son have another meeting with his attorney. I have no idea of what rules she is referring to... but she is governed by the EXACT same rules as a private attorney. The rules are not different... her paycheck simply comes from the taxpayers. The key here is communication. He needs to communicate with his attorney and work with her to build his most effective defense.
His attorney (even the public defender) will investigate the state's case, interview the witnesses, question the police, inspect any documents, examine all physical evidence and photos, research all applicable laws, make courtroom appearances on his behalf and discuss the matter with the prosecutor. Only after these steps are taken will she be in a good position to help your son and advise him on his best course of action.
Without knowing more about the details of the case, it is hard for me to comment further on what types of defenses or strategies he may wish to employ. However, these are all issues better left to his attorney who has experience and credibility in the court where he must appear.
Please reply if I can assist further.