That's what they saw with Payne Stewart's plane. They couldn't really tell what was going on inside because the windows were frosted up. Seems like it would be the same situation here.
More info pointing away from decompression
http://www.newsday.com/news/nationworld/world/wire/sns-ap-greece-crash-theories,0,5234136.story?coll=sns-ap-world-headlines
"Chief Athens coroner Fillipos Koutsaftis said Monday that tests conducted on the remains showed that at least six victims were alive at the time of the crash."
"Some media have reported that the victims froze in their seats before the crash, but Greek officials said the bodies were not cold when they were found."
"Bill Waldock, an aviation safety professor at Embry-Riddle Aeronautical University in Arizona, said one clue to a sudden pressure loss would have been frost on the windows because it's so cold at 34,000 feet. If the fighter pilots could see into the cockpit, the windows could not have been iced over, he said."
Could there have been localized damage to the cockpit?