That is the part confusing the pushback?
Not sure what do you mean with "confusing" it. How the program could possibly know it could pushback as you wanted, if there's no node it could push to ?
There's a simple reason why GSX always want to use an existing node: so it can assume (we can only hope) that if a scenery developer placed a path node in some place, there's aren't any buildings or other obstructions in that place, because that would result in AI crashing into something too so, if there's a node, we can assume it's safe to go there.
What we are surely planning to add in the future, is the ability for, at least for the Custom Pushback option (not the default automatic one), to let you specify any Lat/Lon coordinates, not necessarily those of an existing node, so you could at least solve these borderline cases with a custom pushback, without having to change the AFCAD.
