I'm glad you have faith in me, Pete!
The offender believed the same. He wasn't trying to harm me. He had confidence in my ability to handle a closed post and assumed it would just be a funny joke. I was more perplexed by the breach of etiquette. We are taught not to touch anyone else's gear. Had I found it shut in the water, I would have just opened it. The only scenarios I could imagine the prank posing a legitimate threat would be some sort of rapid rescue or having to donate a reg on the way down. Unlikely, but messing around with other people's equipment and air supply has long been considered a giant faux pas. It's almost an unheard of breach of conduct. The diver just needs to learn that there is a time and a place for practical jokes.
For those who think the guy should be harmed or banned from participating in the sport, I was invited out by a friend who is a captain for a competing dive shop. I spent two days having an absolutely awesome time on a boat that I used to patron quite frequently before I started working for the shop I am currently teaching at. Sure. My friend could kick him off the boat, but then the diver would never have a mentor who can get him squared away. I would rather see him on my buddy's boat, learning from my friend who is a great guy, great captain, and diver. He's the third generation of a legendary diving family here in the 1000 Islands and nobody better for the prankster to learn from and perhaps grow into a diver who will become more thoughtful and responsible. We certainly aren't experts in mental illness, but I don't think the culprit is crazy. He's very well-educated academically, but not from the USA and I think his problem is that he's just young, dumb, and full of ... surprises.