The officer fired Aug. 5 as commander of Beachmaster Unit 2 posted an oblique defense Sunday in the Facebook comments section following the story about his relief posted on navytimes.com. Oblique, because Cmdr. Robert M. Brown said not a word about being fired or the circumstances under which he was fired, instead posting the famous “man in the arena” quote from President Theodore Roosevelt. Brown’s post had attracted a couple dozen comments, most of them expressing support of Brown, and 25 “likes” as of Tuesday afternoon. He had earlier declined to comment until the investigation is complete. Naval Surface Force…