There is nothing satirical about copying an idea.
To repeat: the "Rally to Restore Sanity" is a parody of the "Rally to Restore Honor." And in case anyone is unclear on what a
parody is:
A parody (pronounced /ˈpærədiː/; also called send-up, spoof or lampoon), in contemporary usage, is a work created to mock, comment on, or make fun at an original work, its subject, author, style, or some other target, by means of humorous, satiric or ironic imitation. As the literary theorist Linda Hutcheon (2000: 7) puts it, "parody … is imitation, not always at the expense of the parodied text." Another critic, Simon Dentith (2000: 9), defines parody as "any cultural practice which provides a relatively polemical allusive imitation of another cultural production or practice." Often, the most satisfying element of a good parody is seeing others mistake it for the genuine article.
For some of you, that last line is key.