My understanding was that the property was not fully purchased and that they wanted the location to be a secret until the negotiations for the price of surrounding properties they need were complete. I don't know if they're completed even now-- but one thing is certain-- by finding that document YOU might have blown their cover...
As far as the general idea of Timeship being secret, not true. There are 1300 hits on cryonics + timeship and there have been recent book releases and exhibitions. The book sells for $30 at LEF
http://www.timeship.org/news.html
If the document you found indeed reveals the location, you've scored a investigative journalism coup because the official site says they're still searching.
http://www.timeship.org/site.html