So the question has been raised as to whether a declaration page is actually part of a policy - that is the part that is still out for debate. Maybe the regulators will address it or it can be asked to be addressed when they come out with their proposal on Flood Q&As on Private Policies that is suppose to be forthcoming.
I agree that the industry doesn't really seem settled yet as to whether a dec page is part of a policy as the regulators (surprisingly) haven't said anything about it that I've seen related specifically to private flood insurance and the compliance aid statement. That said, FEMA does provide this definition on their website which seems to state that a declaration page is part of the policy:
"Declarations Page. A computer-generated summary of information provided by the prospective policyholder in the application for flood insurance. The declarations page also describes the term of the policy and the limits of coverage and displays the premium and the insurer's name. The declarations page is a part of the flood insurance policy."This definition of a declarations page can be found here:
https://www.fema.gov/national-flood-insurance-program/definitions