I am under the impression that each and every photo he uploads to Flickr is a work of the United States government and is in the public domain. By licensing them as CC, I think he has committed a copyright violation or the very least, unenforceable restriction.
From: Durova <nadezhda.durova@gmail.com>
To: commons-l@lists.wikimedia.org
Sent: Wednesday, March 18, 2009 7:36:55 AM
Subject: [Commons-l] Rare trove of US Army Medical Photos Heads to Flickr
http://blog.wired.com/wiredscience/2009/03/medarchives.html
Why is Flickr--a for-profit site--getting this rather than Commons?
-Durova
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http://durova.blogspot.com/