Sorry but that is bad information on several fronts. I don't know of a single BGO who would recommend this recommended course of action.
First of all, "holding back till a better score" does not help you as the academy sees all of your scores. If you look at the official score report, it lists prior exams and scores. Secondly, for a junior, this is exactly when you want the academy to make you a candidate so that you can get full candidate status and begin working on the application in time to get a completed app to the Admissions Board BEFORE "crunch time". Getting in at the front of the pack is a good thing for many applicants. Waiting until Sept to send in test scores can lead to candidate status in October and then several months of application elements and DODMERB with completion close to the application deadline.