[Avodah] "God who knows the future"

[David Riceman]

I happened accross a curious Ramban recently (Parshas Shlah, ed. Chavel, 
p. 242):" God, who knows the future, commanded him to send one man from 
each tribe of Israel, and that they be leaders, because God wanted all 
of the aristocrats (gedolim) to share equally in this matter, so that 
maybe they would remember and return to God (ulay yizkru v'yashuvu el 
hashem)."

But doesn't that last clause imply that God didn't know the future here? 
The naive reading of this passage is that the Ramban agrees, if you'll 
pardon the anachronism, with the Ralbag, who says that God can't know 
all the details of the future because that would deny human free will.

Is there somewhere else where the Ramban makes his position clear?

David Riceman