And why would God be selective about applying his ability of forknowledge.
In order to be selective, you first have to know.
The WT gives an illustration of a guy watching a recorded game. He could know the ending, he just doesn't fast-forward to the end for a peek. The issue here is that we aren't talking about some cosmic VCR, separate from God - we are talking about God himself. God is the cosmic VCR.
He would have to know everything before selecting not to know everything.