Interesting, it was information, but not the whole truth. Loki was a exceptional Liar and as such, could tell very well, when he was being lied to. He could tell that while this was not a lie, it was not really the whole truth.
"You're evading, believe me, I chose the Man of Iron because I am sure he is irritating at best. If you struggle with this then there really is no hope for you." Loki spoke, every man had a price and while information on Stark's actual heart was valuable it would not be what would break him. Loki wanted leverage.