In YGOPro "Attack Guidance Armor's" text is: "When your opponent targets exactly 1 monter you control for an attack (...)". In episode 123, Kaiba activated the card while he was being attacked directly.
Also, the art is wrong, the proper one should be:
http://img2.wikia.nocook...tackGuidanceArmor-OW.png 
The card we have displayed there is instead "Attack Guidance Barrier".