From this article: http://www.nytimes.com/gwire/2010/04/28/28greenwire-supreme-court-sides-with-interior-on-mojave-de-46043.html

"Congress had authorized a land swap with the Veterans of Foreign Wars, trading 1 acre of land around the cross in exchange for 5 privately owned acres elsewhere in the preserve."

Congress passed a bill requiring the swap (transfer) by the National Park Service. It was not a giveaway.