Catnip is safe for cats that do react in a hyperactive way to it and safe for cats that dont. Cats can eat catnip. If your cat reacts to catnip in a playful manner then catnip can be beneficial in encouraging play and activity.
The only danger of your cat eating too much catnip is that they might get an upset stomach. Is Catnip bad for kittens. Other than that there is zero reason to worry if catnip is bad for cats. The short answer is yes cats can eat catnip.