Funny Vs Dangerous

Let me set the scene:
I am sitting at the kitchen counter drinking coffee reading the big business owned media's version of what's going on in the world. Jonah is watching Sesame Street. Peter has already left for work.
I'm knee deep in an article about the repeal of Don't Ask Don't Tell and I hear hysterical laughter emanating from my child. Now he loves his SS but he's seen this video 100 times so I doubt it can be from something Grover did. I go over to see what all the hub bub is about and find him sitting on the bass drum of his drum set. How he managed to push the whole thing over with out me hearing a crash I do not know. But needless to say he thinks sitting on the drum is unbelievably funny and frankly so do I. Then he takes it one step further and stands up on the drum, (see photo #2). Ok here is where being a parent gets tricky.
He is having fun, he is purposely doing something to be funny. I love when he does that. He has his Daddy's sense of humor. I want to encourage this type of behavior but....Standing on a drum and jumping up and down is 1. liable to break it and 2.dangerous.
"We don't jump on our toys, do we" I ask. (Peter and I try not to say "No" unless its a serious danger situation.) "Look at you. How much fun. Let's stand the drum set up again and play with it using the stick now." Nothing. The kid looks at me like I'm crazy. He's jumping on a drum while watching Sesame Street and I expect him to stop. What am I nuts? I reach out to pick him up and guide him in an action change.

And then.....CRASH! He tumbles backward. Thankfully he landed on a stuffed animal. He wasn't hurt at all but was a little shocked. A sort of "I was just having the best time, why am I on the floor now" expression.

We pick up the drum set together and start banging away. Smiles, fun, then he tries to climb on top of it.

Ok. So should I have removed him immediately from sitting on it as soon as I saw the situation? Should I have stopped it when he stood up? Should I not have laughed?

I want to encourage his creativity and independent actions. I want him to feel free to repurpose things. A chair isn't just for sitting, put a blanket over it and its a fort kind of thing. But I don't want him to get hurt in the process.
He's a kid, there will be injuries. I understand that. But when do I step in and be preventative and when do I step back. Is it irresponsible of me to let him do something that may end up with a boo boo?