One of the reasons for NOT declassifying stuff even years later is that in future you never know when you may be required to reinstigate plans like this.
No matter how stupid it seems there could always come a time in needing to do something like this. Letting the plans become public you may highlight a weakness that someone was unaware of and plugs.
Once you have allowed a strategy to become public knowledge someone may be able to guess latter stages by looking at what you have done in early stages.