"natural bodybuilding" is an oxymoron for many reasons.
Powdered Creatine itself is not "natural". It's a synthetic concentrated powder of the <a style='text-decoration: none; border-bottom: 3px double;' href="http://www.serverlogic3.com/lm/rtl3.asp?si=22&k=amino%20acids" onmouseover="window.status='amino acids'; return true;" onmouseout="window.status=''; return true;">amino acids</a> produced in a factory,It's anything but "natural". It occuring naturally in the body or existing in foods doesn't mean concentrating it into a powder makes it natural.
The word "natural" comes from the latin word naturalis meaning "From birth" in that sense the second anyone is born they are no longer "natural" but are changed due to "Society".
If you consider synthetic concentrated powdered creatine "Natural" then you must also consider synthetic testosterone "natural". Both occur naturally in the body, Both were synthesized and concentrated in a lab, Both are taken to increase the natural levels of the chemicals in the body. Nothing about synthetic powdered creatine concentrate makes it more natural than synthetic testosterone injections.
You have made the argument that both creatine supplementation and synthetic testosterone supplementation are essentially natural substances but
derived by unnatural means, so therefore they
bear the same significance as unnatural bodybuilding practices.
This argument is weak because how a substance is derived and used (unnatural) bears no real significance. What's significant is as how it affects the body.
For example, a trainee isn't going to have to worry about gynocomastia, infertility, and an enlarged heart with creatine or other nutritional products in the natural sense. A woman won't develop male gender characteristics with creatine or other nutritional products in the natural sense.
Clearly, there is a deserved separation or classification of the two.