The set of spacing requirements for countertop receptacles is one of those rules that is written in ?here is the minimum? type of language. You can do more, but not less. And if you put a receptacle in a space dedicated to an appliance (like the cabinet that is 18 inches above the countertop), then you don?t get to count it as meeting the minimums. All that 210.52(C) has to tell us is that we need a certain number of receptacles.
The question of whether any given receptacle needs GFCI is entirely separate and unrelated in any way. In deciding whether you are required to provide GFCI protection, the one any only one question you ask is, ?Does this receptacle serve the countertop??
If you put a receptacle inside a cabinet located 18 inches above the countertop, then that receptacle does not serve the countertop. How do I know that? Because you can?t place a blender on the countertop and plug it into that receptacle (the cord won?t reach, the outlet is hidden behind the microwave, and if you managed to plug it in you would have a cord dangling dangerously over the countertop).
If you put a receptacle inside an appliance garage that is located on the countertop, then that receptacle does serve the countertop. How do I know that? Because you can place a blender on the countertop and plug it into that receptacle (the cord will easily reach, the outlet can be readily seen and accessed, and if you plug it in the cord will lay on the countertop surface in the usual manner).