I guess I'm not seeing the significance of whether the profile pic of DM was posted a few weeks before, or sometime after, WM's death. If it was before--who knows how long DM planned WM's murder (if that's even what happened, of course)? It's extremely creepy either way, and also ties into the theory that some of us have that DM thought he was untouchable.
If it was just before WM's death: "hey world, look what I'm going to do!"
If it was after: "hey world, look what I did!"
I also don't think the age in the photo matters as much as the fact that the profile did go online so close to WM's death.
I would also be interested in hearing convincing arguments on whether the blood is makeup or photoshop. (Again don't think it matters much, but I am not good at spotting photoshop.)