So maybe its really simple
The island has "magical" powers and is able to "bring up" or "call up"
people places and things that a person needs to deal with.
So since Locke had such daddy issues he was "called up" by him (Locke) so he could deal and move on.
Move on to what? I don't know, possibly the next level of consciousness that he will need to fully understand the island and what goes on there.