Other mistake: When the man at the start is thrown through the room and his head hits the wall, the picture briefly freezes.
Other mistake: When the car chase starts in Vegas in a close up of the two policeman chasing them the driver is wearing sunglasses and the background is badly dubbed. Silly thing to wear when it's nighttime.
Other mistake: When James Bond startles the cat to see which Blofeld it would leap towards to get the correct one, we see it leap to the left. The problem is that the Blofeld the cat leapt at was sitting to the right.
Other mistake: In the opening scene when Bond is looking for Blofield his voice sounds dubbed and the hands we see, etc. are not Sean Connery's.
Other mistake: When Bond first meets Bambi and Thumper, Thumper is lying on a rock directly in front of Bond but for some reason he doesn't see her until she introduces herself.
Answer: If you mean by hiding - why is he never seen normally - then it's because he is a recluse and doesn't like to be seen in public (like Howard Hughes was). If you mean by hiding - why was he not seen during the movie - then it's because he was being held captive by Blofeld and his minions. Spectre didn't want him out and about ruining their plans.
Zwn Annwn