[William Cloud Hicklin]

I suspect he's bluffing (of course, we can't know for sure!). Gandalf's powers are angelic, an instrumentality of Divine will; and, given Tolkien's later writings on the internecessity of hroa and fea in mortals, I can't imagine him approving the radical alteration of an Incarnate's physical body as an upright act. Warping and twisting rational beings seems to be Morgoth's and Sauron's province.