The best man in my wedding will be graduating Marine Corp boot camp the day before the wedding I do not want him to wear dress blues is this OK?

If he were the groom, most would say let him wear his blues. Since he is the best man, he should wear the appropriate suit/tux that others would in the wedding party. If the maid of honor had just graduated boot camp would she be in her blues? Don't think so, and she would be just as proud of her blues as he would be.