Yes, the man found dead hanging from a tree in Atlanta was creating a statement by dying publicly. I believe that if you are going to kill yourself in such a public way, there is a reason to it. Whether it be just for yourself or to make everyone realize a public problem, no one dies publicly for no reason.
Whether or not people who commit suicide in a public manner intend to do so, they do make a statement with their actions. People will see them, and they will receive a great deal of publicity. This will create a statement as it will cause people to ponder over what happened and possibly discover what happened to lead to this occurrence.
Without knowing the details of the hanging, it certainly makes a statement. Hanging from a tree invokes a very particular image, particularly in the South. It is unclear why he did that, and it is hard to say what kind of statement he was trying to make, but it certainly makes one.
Most people that commit suicide in a public manner do not really create a statement. Yes, the suicide will make the news; many times shocking people that hear about it, as well as devastating friends and family. However, public suicides really do not make a statement because most are just focused on the death of someone.