Why?

That was an interesting post. Information like that is hard to find for non-Finnish language readers here in the USA.
Jukka K. wrote:
...
However, the high command of Finnish army had practically closed their eyes to a possibility of Soviet attack. While the soldiers knew attack is coming the high command had not made any preparations for defence, and the generals had even "shielded" the War Marshall Mannerheim, Finnish military commander, against any suspicions of such thing. The generals, as it seems, had even intercepted and stopped recon reports about possible Soviet offensive before they landed to Mannerheim's desk.
...

My question now is why was this so and what reasons were given?