Lewis's quote doesn't pertain to a scenario in which God pops up and tells you what you're gonna do tomorrow, though, like River told the Doctor. The issues that arise are much more salient then: to paraphrase someone from another community, if someone told you you would have blueberry pancakes next Saturday morning and you would wash them down with coffee and say "mmm, that was good", would you really feel that way, or would you be going through the motions because you were told that's what you'd do and how you'd feel? Much as I love Moffat, I have major problems with his timeloops and their ensuing elimination of free will.