Just because something is a legend does not mean it is not true. I can speculate that General Schwarzkopf didn't say it, but that is no different than speculating that he did. He lives here in Tampa, maybe I should drop by and ask him?

As for the Republican Guards being spared, I think you will find General Schwarzkopf was not at the top of the decision loop. He was probably ordered to let them go based on some series of decisions arrived at by Bush and Powell. It is not like the Republican Guard could outrun F-16s, A-10s, and F-15Es. It was a conscious decision of our government to leave Sadam in power with adequate forces to protect himself.
Unlike MacArthur in Korea, General Schwarzkopf did not speak out publicly against the decisions of his superiors regardless of their validity. He carried out his orders as he should: with honor and dignity. Many reasons have been provided and postulated, but we can only guess why the powers that be chose to let Sadam and his Republican Guard survive.
Personally, I hold George Bush Sr. responsible for the results of Desert Storm. Overall, I think George Bush Sr. has been one of the most influential men in the history of this country. He started as a Navy pilot in WWII, directed the CIA, wrapped up the Cold War, and led the country through the most one-sided victory we have seen since the Spanish-American War. I leave it to later historians to debate whether his influence over that span of 50 years was for the better of the worse. As a bonus legacy, his sons are stepping up to fill his shoes, almost like a royal family (a backwards step in American history in my opinion indicating how much birthrights still affect our social-political status).