No, we're talking about the same thing and I'm saying you CAN run Windows 8.1 on a Mid-2009 MBP w/ Boot Camp 5. How do I know? Because that is (well, was until a recent reformat) my current setup, lol. All it takes is bypassing Apple's 'no go' screen by installing Boot Camp 5 via the command prompt.We may be talking about two different things. Windows 8.1 is now fully supported under Boot Camp 5.1, assuming that the hardware is compatible. But in this case (Mid-2009 13" MacBook Pro) it's a hardware limitation per http://support.apple.com/kb/ht5634 - expand the section MacBook Pro and look for the Mid-2009; it only supports Boot Camp 4 and can't run Windows 8 (BC4 does not support Win8, and the BC5.1 drivers don't support this hardware).
edit: I should note this DOES require you to already have Windows 7 installed under Boot Camp 4.