DBCCShrinkDatabase as Security Cleanup Measure?

Recently a private document wasposted to a publicly accessible SharePoint site. The file was deleted and removed from the search index by running an intermediate crawl of the content database. Now the client wants to shrink the database, which is just under a 1Tb in size and sits on a SAN, claiming that this will insure the file is gone. From what I’ve learned so far this is not guaranteed to really overwrite the address space marked as recoverable. Is there any validity to the notion that shrinking a db is a good way to truly remove the file from Sql Server 2005 (or any sql server maybe) and is there a better method to inusre that a file is truly gone at the byte level?