Windows has an interface for doing what you asked. It had a bug / didn't work as described so they fixed it. Your company wont buy the fix, but that doesn't mean the fix doesn't exist. It means you can't take advantage of it, sure.
But saying Windows doesn't support it is deliberately misrepresenting Windows to make it look bad. It's spreading FUD, and it's wrong.
Plus, why did you bring WMI into this? You can't seem to do it with WMI: http://msdn.microsoft.com/en-us/library/aa394595(VS.85).aspx "If you are not using DHCP, you cannot use WMI to disable a network connection". Were you just bringing WMI into it because it sounds scary and complicated and so would help shore up your FUD, or is there a way and this MSDN article is wrong?
(But you can do it by scripting the shell: http://mcpmag.com/columns/article.asp?EditorialsID=619 or by using Devcon to disable a hardware device from the command line: http://support.microsoft.com/kb/311272/en-us )