He should definitely be represented by an attorney. If he cannot afford an attorney, he should request the opportunity to apply for the services of the public defender.
Whether the prosecutor will elect to pursue the case or agree to a dismissal will depend on how the police officer portrays your son's actions in the incident report and other evidence that may be available to the prosecutor (such as video recordings). He very well may qualify for a pre-trial diversion program that could result in the charge being dismissed and possibly expunged after he meets certain conditions. Eligibility for a diversion program depends on the facts of the case, his record and other factors.
I recommend that he speak with me, or another experienced attorney, if he would like to discuss his case in more detail. If he does not wish to engage the services of a private attorney, he should definitely request the services of a public defender and not try to go through this process alone.
DISCLAIMER: This answer does not constitute legal advice and no attorney client relationsip has been, or will be, created until a valid engagement agreement is signed. No duty arises from this posting. Answers posted here are general and made with limited knowledge of the actual facts of your case. Always speak with an attorney licensed to practice law in your jurisdiction if you wish legal advice specific to your case.
Your statement that your son is "scheduled to meet with the solicitor but not sure why or what to expect" should be indication enough to you that your son needs a lawyer. The prosecutor is not on your son's side and if the prosecutor believed your son should have never been arrested, he/she could have dismissed the case without your son ever having to go to court. If you have the means to help with I would hope you would hire him a lawyer as your son will get much more personalized service from a private lawyer than a public defender. Please contact me if you would like to discuss his case in detail. 404-812-4305.
I agree that an attorney is needed. If you are interested, I answered a very similar question yesterday and discussed the disorderly conduct statute. It can be found in the link below:
This response is for informational purposes only and does not create an attorney-client relationship. Please note that the information I provide is for the state of Georgia only and should not be used for any purpose in any other jurisdiction.