There is no way that two random kernel engineers pushed a feature that allows booting unsigned kernels on Apple hardware (I'm assuming that's what raw image is?). I don't know how _high_ up it goes but I am very certain it was not some low-level skunkworks thing.
You're assuming wrong. Booting unsigned kernels on Apple hardware has been possible since January. This just makes it slightly less annoying since you don't need to build a Mach-O binary to do it, and more future-proof since it decouples it from Apple's binary format which they can change the requirements for at any time (as they did this time). It means I don't have to go off and reverse engineer what the new requirements are, I can just stop using Mach-Os and know the raw option will never break (assuming it continues to exist), since there is nothing to break with a raw file.
Apple's machines are designed as an end-to-end ecosystem that suits their needs, and that they can change at any time - open, but without stability guarantees. This feature is effectively an acknowledgement that people using these machines outside of their ecosystem exist, and might want some stability guarantees.