I'm a freelnce video game journalist and also write for the video game site Retry.se. We got the Killzone 2 review code just before New Years Eve and the embargo for the review in printed media was January 5th and for online media it is on February 2nd. So I think it's safe to say that everyone, regardless of their score, have had plenty of time to play and review Killzone 2 on their on terms.
So I don't think that Sony is manipulating anyone :)