No it's not. Microsoft has to disable outdated and vulnerable signed bootloaders to stop them being used for secure boot bypasses. Microsoft worked with RH to get things updated which they did, it's just distros for caught slacking and were shipping an outdated vulnerable boot loader.

I know it's the norm to bash Microsoft and they do a lot of crappy things, but in this case it was just certain distros not taking security updates seriously, which is why a lot never broke (such as Fedora)