I wonder why not??
No idea. I can see not releasing details of the autopsy report, but they should at least release the identification at the first oppty - a lot of people have spent a lot of time trying to help find Hannah, not just LE, and the vacuum is being filled with unease.
In most cases, identification is done "quickly", like 24 hours - they can, and should, withhold any information that might jeopardize the case - but if there's one person who knows whether that body is HG, it's JM.
Edit: quickly overcome by events - a written statement will apparently be released, certainly adequate to the task.