My guess would be that it started to get contentious, and TR, (WSB Editor) had to delete it.
Sometimes she’ll simply remove any offending Posts, but if that would drastically change the continuity of the Thread, or there was too much to wade through, she’ll delete the Thread entirely, or at least close it to new Posts.
In either case, IMHO, WSB doesn’t delete Posts/Threads without good reason.
Mike