For all intensive purposes, he was dead. It's likely DC would support that statement. To give pause, look up these creatures called water bears.
http://www.museums.org.za/bio/tardigrades/index.htm
http://en.wikipedia.org/wiki/Water_bear
"Cryptobiosis
The way that tardigrades have adapted to environmental stress is to reversibly suspend their metabolism and to effectively isolate themselves from the changes. This state is known as cryptobiosis and is a truly death-like state. Cessation of metabolism in other organisms is called death. Metabolism in tardigrades can lower to less than 0.01% of normal, or be entirely undetectable and the water content of the body may decrease to less than 1%. Tardigrades have been revived from this state after more than 100 years and shown signs of life! However, experiments have only shown cryptobiosis under natural conditions of 12 years but frozen they could theoretically survive for ever!"
Since kryptonian physiology is unknown, it can be argued that Superman was either dead or in a cryptic state. Don't assume that Superman dies like a human being if the writer hasn't stated so. In real life, a scientist could examine a water bear and possibly come to the conclusion that it's no longer alive, due to the uncertainty of the tools and so forth. Despite all that, I'm sure if superherohype asked Mark Weid or someone like that if Supes' actually died, the man would say yes.