I´m not sure I´m following you here, but why would Sayid want to start the creation of Ben, the monster? The one who probably is responsible for the killing of Sayids one, true love?
He's not. He's interested in recreating Ben as something else.
Let me put it this way. Ben infiltrated the Dharma group for years and years.
Now suppose you relive all of that in reverse, but Ben infiltrates both groups?
Ben never became what John did, who can and does walk between both groups easily. But John is an outcast in the outside or "real world," whereas Ben is a well-connected and sophisticated and devious player in both the real world, and on the Island. Think about what that means. He's Satanic. He fits in everywhere, but he can't really achieve anything anywhere. John fits in no-where, and yet he is the Key to the Kingdom. Ben can steal the Keys to the Kingdom, and set the prisoners temporarily free,
but he can't be the Keys to the Kingdom, and fix things more permanently.
That being said the show can't continue to progress forever from the 1970s to the now. It's too big a period of time to cover. So certain things are going to have to be compressed and then dislocated both forwards and in reverse.
What I suspect the Island wants is to re-write the past without changing it.
Because you can't change the past, per se,, but what you can do is add to it (and/or subtract from it) to such a degree that it comes out different.
Or, let me put it this way. You can't reform a man by going into the past to change his past. But in order to reform a man must go back to the beginning and start all over again so that he comes out in a different place than where he left off when he started his reform. You rewrite the past not by altering it, but by altering yourself. You rework the past when you rework yourself. The old things come out different even though they never changed.
And if Ben becomes altered, so does Sayid.
If it works then it doesn't just help Ben, it reforms Sayid.
It's a kind of resurrection.
But resurrections never happen til the Old Man dies.
So the Old Men keep dying.
Til they don't need to anymore.