While I applaud the searcher who found the remains, he was a Sergeant with the Chesterfield Sheriff's Department. Even if he was super excited, he should have known better than to release the details that he did to the media. With all due respect, it wasn't his place to reveal those details - it should have been up to the overseeing police agency (whether Albemarle, C'ville or the VSP?). Besides, we don't know what details were given to Hannah's family - maybe the police just called the family and said that remains had been found with no further details. It would be pretty callous for them to have learned those details through the media.
Someone had mentioned that maybe the release of the details would compromise LEs bluffing ability with JM - since he's lawyered up, while cops may speak to him with his attorney present, I'm pretty sure JM has been advised to keep his mouth shut at all costs, so I doubt the cops could have gone to him and evoked any kind of response - his attorney wouldn't have allowed that. Also, at some point, JM's attorney will have access to every piece of evidence that LE has - so I think JM and the attorney are just waiting until they see exactly what evidence LE has. It's in his benefit to keep his mouth shut.