Except for the fact that it is the pretext for the entire document.
Nowhere in the Constitution itself can you find the idea that the preamble is not binding. In fact, nowhere in the document is it even called a preamble. We just call it that for the reasons of identification. It is the cornerstone for the Constitution, laid first, intrinsic to any decent understanding of it.
Cite me ONE instance of a prescriptive statement that could even potentially be considered a binding provision in the "preamble".
Then cite me even ONE case where a decision of the Supreme Court was grounded in that statement.
I'll wait.