30... Ra2+ is already crushing, and Kc3 is the only defence.  The played 31. Kd1? should have run into 31... Rh2! threatening both the knight and back rank checkmates.  For instance, 32. Re2 Rh1+ 33. Re1 Ra1+ wins the rook, and 32. Nb1 Nb3 threatens both the rook on d4 and another Arab checkmate on d2.
30... Ra2+ is already crushing, and Kc3 is the only defence.  The played 31. Kd1? should have run into 31... Rh2! threatening both the knight and back rank checkmates.  For instance, 32. Re2 Rh1+ 33. Re1 Ra1+ wins the rook, and 32. Nb1 Nb3 threatens both the rook on d4 and another Arab checkmate on d2.