Any legal convictions raises potential issues with USCG licensing. Read Section III of the License application CG-719K.
The application asks if you have been convicted by "any court for an offense other than a minor traffic violation?" It also mentions reckless driving specifically and a conviction of a traffic violation related to DUI.
The app definces conviction as - Conviction means found guilty by judgment or by plea and includes cases of deferred ajudication (no conte st, adjudication withheld, etc.) or where the court required you to attend classes, make contribution of time or money, receive treatment, submit to any manner of probation or supervision, or forgo appeal of a trial court finding. Expunged convictions must be reported unless the expungement was based upon a showing that the court’s earlier conviction was in error.
Don't try to game the system in any shape, way or form by playing word games. I have heard of guys having the Coast Guard show up on board to revoke a license in person once they figured out that the mariner was less than honest on the application. "I didn't thank that applied to me" isn't usually a good enough excuse either.
I could go either way on whether or not to tell the Academy. I can see good reasons to tell as well as to not tell yet. I doubt that DS will be able to get by without telling them at all, or at least them finding out. Them finding out on their own can be bad on its own. I can also see a scenario where the Academy determines DS to be un-licensable and so no reason to continue his course of studies. He should prepare himself for that as a possible outcome.