Ah, no.

=> Ambient occlusion is diffusing existing incoming light back into the scene.

=> The Ambient node "adds" light. => That are 2 completely different things.

Say, I have a light that shines on an object. The object absorbs some of the light and diffuses the rest back into the scene. => That is ambient occlusion when 2 objects are close together.

The ambient node "adds" light and can be used to make TV- or Computer sreens emit "new" light. Or to make Neon lights emit new light.

2 completely different things.

But : Read this : If you have a nonsensical material, such as using the old AO node, Superfly will ignore that node when it renders; after all, Superfly inherently takes AO into account, so using the old Firefly cheat doesn't make sense.