My point exactly - the existence of the Predictor proves more than lack of free will. It's lack of free will, so we are automatons that respond to stimuli in a deterministic way, sure.
But there are also some strong restrictions on the set of reactions that are allowed, for example none of them can lead to a functioning counter-predictor robot.
I spent way too long thinking about this and getting annoyed before remembering that Predictors aren't real.
Don't mess with time travel.