Might be a bug. I had replied in the thread so I could find it from my notifications. When I then went to the "community" board, there it was. I then went ALL the way out and back in by clicking the "FORUM" button on the top of the main Shopsmith page. I could see the thread then, but it was greyed out so I don't think it would have been visible to someone not a moderator. I was offered the option to "restore" it, so I did. It's no longer greyed out so I think it should be there for you now.
On the old forum there was a moderator's log so we could see what actions had been done. If there's one on this iteration, I've not found it, so I can't see if deleting it was an intentional action.