How does that stop Apple from supporting Vulkan on their system? It is pure political sabotaging. And you can't pull any excuses like "it requires effort". Apple have pools of cash to do the right thing for users and developers. They simply very intentionally oppose it due to their dinosaur lock-in mentality.
A blog post is different from a real compliant commercial implementation. Other reasons you couldn't do it include eg someone with a patent on it won't license it to you.
Mesa's implementation will get a compliance certification once it's ready. I don't see why they would have problems with that - other Vulkan drivers got compliance from Khronos once they passed needed tests. Patent FUDs are nonsense - no one else has such issues and many drivers already exist and work fine.
The real reasons are not good at all (i.e. Apple's obsession with lock-in) and have no excuse.
