I've been meditating on this, and hit upon two things.

First, there's another way that this duality can be resolved, and that's that both astrology and geomancy are purely subjective. Subjectivity doesn't necessarily imply that results aren't repeatable. If an artist paints the same scenes over again or uses the same techniques over again, does that imply that their art is objective? Of course not, it simply shows their preferences. Perhaps our world simply enjoys astrology (or any other set of physical systems) working the ways it does, and so expresses it in matter and personalities and so on over and over to explore how it plays out in all its many combinations.

Second, we are taught that there are objective phenomena (natural "laws", physics, chemical processes, etc.) and subjective phenomena (the mind, personalities, the arts, etc.); but this need not be so. We can't readily dismiss subjectivity, but if the universe is a Being and simply repeats itself for the fun and interest of it (and not because "that's the way it works"), then we can (and, by Occam's razor, should) dismiss objectivity as being part of our model of the universe.