I have a slightly different reading on Ted Chiang's approach to free will.

As I see it, free will is a perspective - not something true or false, just looking at things from a certain angle. Knowledge of future is another one - and it is incompatible with free will. You can choose, you can know the future, but not both.

I think free will should be understood as a game of repeated prisoner's dilemma game. Where we have to tweak our choices of whether to choose vanilla or chocolate based on our past experiences. Free will emerges in this repeated version but then determinism can creep in there too.