I have no idea what threads were deleted but I have posted on this matter before.
I was having a GN accuse me of various things which were untrue and the thread was quite nasty. I was dealing with it but GN deleted the thread. I urged GN to reinstate the thread as I felt the other GN's should see for themselves what had been said and my response. By deleting the thread the poster had made her feelings known and the damage was done.
I urge G.N. to consider leaving such threads and openly chastise the offending poster/posters to defend the GN who is being aggrieved. If, as I was, not aware of the comments on the day, then it is an unfair position to be in. Nobody should be spoken of behind their back in a derogatory manner without the right to defend themselves. Delete a post, yes, delete a thread, no.