(defn if-any-then-all [val mat]
  (let [M (count (first mat))]
    (map #(if (< (count %) M)
           (for [i (range M)] val) %)
         (map #(remove (fn [x] (= x val)) %) mat))))
(if-any-then-all 5 [[1 2 3] [4 5 6] [7 0 8]])
=> ((1 2 3) (5 5 5) (7 0 8))
(if-any-then-all 0 [[1 2 3] [4 5 6] [7 0 8]])
=> ((1 2 3) (4 5 6) (0 0 0))