Well, that's OK for Microsoft because it'll presumably push out an update to its bootloader to no longer be a blacklisted one at the same time.
Shame if it decides to blacklist the Fedora key. All of a sudden every single secure-booted instance of one of its competitors that is dual-booted with Windows has stopped working! And there is, as far as I can see, no easy way to recover. (Maybe Fedora could make a boot CD image available that would update the bootloader, splash it in big letters all over fedoraproject.org, and hope that everyone affected thinks to look there. *shiver*.)
(I have 'secure boot' on this new system of mine. I have, of course, turned it off. The last thing I need is a way of rendering my system magically unbootable. I have enough of those as it is!)