Can you explain a little more about what you are trying to accomplish? The setup page is used for more than showing status--it's for installing and upgrading the site and supporting features. For security purposes, it should be used only by administrators, and if an error occurs it will be shown within that page so the viewing administrator can take care of the problem.

The assumption is that the site database should always be available, since web sites are up and running 24 hours a day. So if the database is inaccessible, that's considered a critical error needing administrator intervention, so it redirects to the setup page. I don't know of any way to accomplish what you want to do without forking the code. We don't recommend forking, since that will make it very difficult to upgrade in the future.