Epic mentioning the Microsoft UEFI CA and then saying they want the list open source later is a funny mix of practical and idealistic. It sounds like they know they need the boring infrastructure stuff first, which is probably why this has taken so long. If they can make it work with Ubuntu, Fedora, openSUSE and SteamOS type setups, that is already a decent baseline. The real test is whether developers actually bother to enable it once the tools exist.