Here's why:
* Jinzo's effect: Jinzo's effect states "While this card is on the field, your opponent cannot activate Trap Cards." This means all Trap Cards, including Counter Traps, are negated while Jinzo is present.
* Counter Traps: Counter Traps are a specific type of Trap Card that activate in response to an opponent's action.
Therefore, as long as Jinzo is on the field, your opponent cannot activate any Trap Cards, including Counter Traps like Negate Attack.