"The other get-past-the-prior-art inclusion in the patent application is height – so if, for example, you're closer to an access point known to be on the second floor than the first floor, Apple can guess that you're on the second floor."
How would it know you are closer to 1 point and not another? Say there is router on floor below you and you are standing right above it and other is at other side? Then it could say you are on 1st floor not 2nd?