why doesn't this print the result of {:tag audit-rootkey :attrs {} :content (map to-xml-struct directory-records)} to stdout?

gistfile1.clj

(defn generate-file-audit-xml
  "Takes a seq of DirectoryRecords that contains the file audit and outputs an XML string with a
  top level element with the value of file-audit/audit-rootkey"
  [directory-records]
  {:pre [(sequential? directory-records)]}
  (let [out *out*]
    (-> (binding [*out* out] {:tag audit-rootkey :attrs {} :content (map to-xml-struct directory-records)}) 
      xml/emit
      with-out-str)))