It's worth noting that the position in the photos is not a legal chess960 start position. The best shot of the position is the photo in the lower left, which shows the pieces set up as either NKNBRRBQ or NQNBRRBK. Although it's not completely clear which piece is the King and which the Queen, in neither case is the King located between the Rooks, as required in chess960. Gligoric's Shall We Play Fischerandom Chess? allows us to date the photos to 1993 (p.36-39).
During Fischer's stay in Saint Stefan in 1992 [the second Fischer - Spassky match], he recommended shuffling all the pieces at random on the back row before the beginning of each game. [...] It turned out that Fischer's first plan would make 2400 different commencing positions. Immediately after his sensational return to the chess scene in 1992, he began experimenting privately with this kind of chess against colleagues and chance visitors.
Although Fischer was pleased that the mathematical sum of starting positions was very large, he soon discovered that eventually having two Bishops of the same color made an unpleasant impression, producing one-sided and limited opportunities on the chessboard. It was also clear that obstructing the right to castle would mean a step backward toward the primitive distant chess past and if the intermingling of pieces on the back row made castling impossible for both sides, this would inflict irreparable damage on playing strategy as well.
The result of Fischer's constant meditation on how to give alternative life to the game of chess, threatened by the exhaustion of its creative resources, was the formulation, in September 1993, of the rules of "Fischerandom Chess".
For more about Fischer's original rules, see Fischer's Rules of Fischerandom.