Conditional logic for taxonomy and other fields has been discussed here before and the developer has said in the past that he’s working on it. I’ll mark this topic for him to take a look at. He has a lot on his plate.
In the mean time, my suggestion, if you really need to have conditional logic based on a taxonomy would be to use a select field that has dynamically generated choices. http://www.advancedcustomfields.com/resources/dynamically-populate-a-select-fields-choices/
