So what is the prime objective?

So why does Ben have Sayid become an assassin, after he leaves the
island?   Is it a case where these people are somehow linked to the
island in the past.   Thus if they're killed, it stiffles the transfer
of future knowledge back to an earlier time period in their life.  ..IE:
A battle is being fought over opened up time lines... Where people
essentially can exist on a level where they are aware of not only past
memories, but future memories too?    ...Jon