Ben lies because..... by dislodgedintime

Ben lies because he is is told to by the Losties in '77. Think about it. From the very beginning Ben has been involved with the main characters we know and love. Jack, Sawyer, Sayid, Hurley, Jin, Miles, Juliet, Kate, and Daniel.

Think about this, Jacks plan works in some round about way. We open up in an Alt timeline. The Losties figure out what needs to be done.

So

The Losties tell Ben that he needs to make sure the Losties come to the island and do not leave...no matter the cost. This might explain how Ben knows certain things and why he does what he does. The Losties stuck in '77 tell young Ben to make sure that he does things to make things happen.

So in the future Ben knew the plane was coming, he knew who would be on it, and he tried to control all aspects of the Losties actions and prevent them from leaving because.