My DH ate from the kid's menu at PSB lunch but was charged as an adult.
My 10 year old was handed the kid's menu at several restaurants last year.
At a regular 'menu' restaurants, adults CAN order off the kid's menu if they want to, however, if you are on the dining plan, you will still be charged for an adult TS credit even if you order from the kid's menu.
It's the buffets, all you can eats and pre-plated restaurants that they care. You will be charged the adult price for those meals.