My former neighbors had a child like yours. He wasn't gifted. The kid wanted OUT of the house, and that was that. His favorite places were the road and into the neighbor's yard where the mean dog might be. Or maybe he'd just take off along the sidewalk and strike out looking for adventure. Who knows? He was not quite 2.
They put a bolt on the door. He used a chair to unlock it. They eventually had to put the lock so high, his mom could barely reach it. That stopped him. Can you do that?
I agree with the other posters about the forklift, and will add that blaming the operator (keys) for failure to watch your son wasn't a good move. They were right to tell your DH to leave. I know I sound really harsh, but it's important to recognize how much damage your son could have caused, either to himself or others. You can tell yourself that he's very bright and knows about the controls and etc., but you also said that he just does stuff because he wants to. How is it that he's so bright, he can be responsible by himself inside a forklift, yet he doesn't understand that it's not okay to just take off or climb inside it? How do you know his independent streak won't suddenly manifest itself when he sees a really cool switch? Having been in a forklift before might have made him MORE confident about playing with it. What if he'd flicked a switch and caused the forklift to do something unexpected when the operator turned it on? What if he'd slipped and fallen on a control or injured himself? What if he'd taken the keys?
In this respect, I disagree with indigo. You should be hard on yourselves. Try to see this incident as "we dodged a bullet" rather than "it was okay because he's so bright." Seeing it as the child wasn't in danger could lead you to very serious problems next time.
It's very difficult to watch a little kid who's determined to go exploring. I've had to search for kids who took off to look for fossils or a better toy shop. It's hard. And knowing that, sometimes the answer is to leave the child at home. I didn't like to take my kids to places like Lowe's at that age because of the dangers, and avoided doing so whenever possible.
