SharePoint 2010: How can I KEEP User Profile entries?

I have an odd problem - My SharePoint 2010 site is working fine. The User Profile service is doing what it should be doing. It syncs automatically with the Active Directory, and all addition/deletions/changes in the AD are picked up in the Profiles. 

My problem is that I want to KEEP the User Profile entries even after the users have been deleted from the AD. Is this possible, and if so, two followup questions:

1. How would I do this, and 
2. Would it be dangerous/insecure?

Thanks,

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Keith Vollero