Is it possible to save memory to prevent OOM-CTDs when excluding AES-serviced airports from GSX?
Surely not.
GSX doesn't take ANY memory if you don't call it, since its own logic runs entirely outside the sim (under the Couatl.exe process, so it has ITS own separate VAS). It will start to take some memory only after you start calling the services, which will cause objects/textures to be created.
So, the simple solution, instead of excluding airports, it's just not call GSX.
But don't think you are "saving" any memory using AES. In fact, it will be exactly the opposite: since AES runs entirely in-process (it runs in a .DLL, so it takes away VAS from the sim not just for the objects, but for the program logic, too), you are going to waste even more memory this way so, it would be best doing the opposite, and use only GSX, calling it only when you think there will be enough memory available.