Is this the correct forum to ask about arcpy.SelectLayerByLocation_management using XYZ coordinates?
(If not, please send me a link)
If you're using Python, ask here.
Ironically, the question, "should I ask a question about arcpy in the Python space?" should go in some other space, since it's not a question about Python, but we'll forgive you. Just do your best to put the question where you think it should go - there aren't any real repercussions to doing it wrong.
And the actual question has been posted Help using PointGeometry with SelectLayerByLocation
Retrieving data ...