That sucks that someone would ruin it and steal your lock.
As a side note, what is the etiquette on using someone else's tree stand. I saw one last year that was permanently attached to a tree with spikes nailed into the tree for a ladder. Is it cool for me to sit in it if the owner is not around?
IMO, it's never OK to sit in someone else's stand. It's like finding someone's ground blind on turkey opener (which I've seen) and crawling inside. I know of several duck blinds on the Sea built by friends of friends and, likewise, I would never think of hunting them without permission.
I wouldn't even mind if they sat there but the cutting/theft of the lock was odd to me. Anyway, I don't care that much about it and my fuzzy pics don't matter. If I run into this dude I'll take care of it. He'll know who he met. No worries.