[Rover]

I read once somewhere, that the third party lenses have to fake being a Nikon (Canon... etc.) lens, and pretend to be some existing Nikon lens so that things work. The actual lens data is still being read then from the lens correctly though. I presume there is something like a lens database in each body that checks if a valid lens is mounted, in order to initiate communication protocols. Once communication is established, the body can read all lens parameters from the lens firmware, and apparently doesn't double check. I guess if Nikon/Canon etc. wanted to be nasty, they could do that and prevent the lens from working, although they might have some anti-competitive lawsuit coming then.

Anyway, it seems you encountered an interesting point now with MFA that is lens-tied. If one is unlucky, a third party lens someone is using has the same ID as a OEM lens they are using, and since the body doesn't know that it's a different lens, applies the MFA...  I guess that's a caveat for using third party lenses, if you use MFA. 

Presumably the Micro Nikkor here was chosen because it's a less common lens that 24- xx zooms.

I've heard this as well, but if that had been exactly the case, how come older bodies work flawlessly with newer (original) lenses? For example, my 16-35 II was released way after my 1D Mark II N body, but works all right (mind you, there seems to be no lens designation written down in EXIF while every other Canon lens I own is recorded (70-200/2.8 IS, 24-85, 50...)