Porque ele sabe que a fonte de energia de Zeus não é ilimitada.
Esta solução é uma estratégia de boxe bem conhecida, conhecida como " Rope-a-dope "
The rope-a-dope is a boxing fighting style commonly associated with Muhammad Ali in his 1974 'Rumble in the Jungle' match against George Foreman.
Technique
The rope-a-dope is performed by a boxer assuming a protected stance, in Ali's classic pose, lying against the ropes, and allowing his opponent to hit him, toward the end that the opponent will tire and make mistakes which the boxer can exploit in a counter-attack. By leaning against the ropes, much of the punch's energy is absorbed by the ropes' elasticity rather than the boxer's body.
Há também uma menção em trivia do IMDB
Charlie Kenton's idea to wear down Zeus's power supply by allowing him to repeatedly land blows on Atom was in fact a technique used by real life professional boxer Muhammad Ali. Nicknamed the 'rope-a-dope', Ali utilized the strategy to tire fellow boxer George Foreman, a much stronger opponent than himself, and eventually gain victory. Ali famously angered Foreman with phrases such as "Is that all you got, George?" during the fight, mirrored in the film by Kenton's taunting hand gesture.
Esta é também uma técnica strongmente associada a Rocky Balboa, mais precisamente em Rocky III E há muitos outros links que você poderia fazer entre a série Rocky e o Real Steal.