When the issue of an ethical code was raised, my natural assumption was that it would be posted on the site. However, the person I was speaking with preferred it to be an internal code. While she does not have the final say, she is in a very influential position to be heard on the matter. Unfortunately, she did not elaborate on her reasons against transparency.
I assume it has something to do with the potential of the ethical code not being financially viable given changes at the company. One can imagine that publicizing an ethical code and then rescinding it would, of course, create a tremendous amount of bad blood.