Why would you introduce AO to SSGI though? AO is an old trick originally designed to fake indirect light occlusion in areas lit by fake constant ambient light contribution. Later, in some earlier inaccurate offline renderers, it was used to introduce indirect illumination occlusion detail for extremely inaccurate global illumination solutions, such as Final Gathering in Mental Ray (which had especially poor Final Gather implementation) or Irradiance Cache in VRay.
But SSGI is neither of those. It’s not just constant ambient light, or is terribly inaccurate when it comes to spatial detail density. Introducing AO into SSGI would give you worse, less realistic results and additional computational overhead at the same time. Or in other words, your rendering is slower and you get worse quality in return. A loss/loss scenario.
There seems to be indeed occlusion already built into SSGI already, and I believe that any attempts at artistic control of it will just give you more bias and reduce realism. And trust me, despite what you may think, there’s nothing artistic about overkilled amount of AO in scenes, unless your artistic intent was to simulate consistently uniform accumulation of a smoke ash in concave areas if your map 