Strange "locked thread" & Icon... Help?

In the Parent Cafe, a thread I had been participating in about dangers of occasional smoking was recently locked… I was wondering whether the thread creator can lock the thread, or whether this was an administrative thing? The discussion was getting a little heated, but it contained a lot of good information.

If thread creators can lock their threads, doesn’t that hurt the CC forums in terms of expressiveness/discussion? Or are posters encouraged to make new threads? If so, can any moderators confirm that the thread wasn’t locked for censorship? If you guys don’t want people posting about smoking on these forums, that’s understandable… I’d rather be on the right side of the rules.

I locked the thread because it had deteroriated into bickering and there wasn’t new information being shared. If you want to start a new thread and people will refrain from negative comments about each other, I’ll allow it.