It is a legitimate concern. I would suggest calling an attorney in that county to advise you and to handle the charge. It may be possible to either get diversion and pay off the community service hours or to have the charge dropped or dismissed, depending on the facts. These options will not be available by mail. Instead, an attorney can speak to the prosecutor and make a case for your son. Or, there may be some defect in the citation or charge a lawyer can exploit on your behalf.
If there is no other option but to plead guilty, or no contest, an attorney can tell you that and assure that he gets a withhold of adjudication so that he can then get the record sealed in the future.