The parent of this comment looks to have been deleted (the parent link says "this space intentionally left blank"), but in the comment thread it displays as if it were a child of this comment. It doesn't display as a child when linking directly to that comment though.
I have seen this too, elsewhere. As it is, we can delete a comment, and although the author can still see its existence, no one else can. To fix the problem, you'd have to make a rule where after someone replied to the comment and the author then deletes the parent, the old post reads '[DELETED]', or whatever you like. It probably shouldn't reveal the author's identity. You're still preserving the architecture of the thread. That's just how I'd fix it. I have no idea how easy to implement it would be within Hubski's architecture.