"fair play" deleted, why?

"Ah! my good friend, let this wild mountain air have fair play; let us with the desert's freedom joyously float convention and opinion—upstart usurpers!"  "Scenes Beyond the Western Border," Southern Literary Messenger  (August 1852): 508 

 In revision for the 1857 book version, "fair play" was deleted, thus:

"I am only in a mood; buoyant and bitter; tameless as the Arab coursing his native desert; free as yonder soaring eagle! it's this wild mountain air! Let us have a fling at the world,—the poor dollar-dealing sinners, cooped up in their great dens—"

Friend.—But you began by a fling at me—

"Only a love tap, Friend; my way of argument. Let us with the desert's freedom joyously flout convention and opinion—upstart usurpers!"  (Scenes and Adventures in the Army)

 Why delete "fair play"?  Uncomfortably close to, or evocative of, Ahab's language in Moby-Dick (1851)?

"Talk not to me of blasphemy, man; I'd strike the sun if it insulted me. For could the sun do that, then could I do the other; since there is ever a sort of fair play herein, jealousy presiding over all creations. But not my master, man, is even that fair play. Who's over me? Truth hath no confines."  (Moby-Dick, chapter 36)

 "'Avast!' cried Ahab; 'let's have fair play here, though we be the weaker side.'" 
(Moby-Dick, chapter 119)