Goodness, this seems to be getting a bit self-important and bombastic. It's Gransnet, not a well-funded newspaper or broadcaster with a team of lawyers who can check not only the content but also the wording of comments about a contentious issue. Libel law is such that the latter is just as important as the former. It is surely reasonable to delete a post that is potentially libellous even if it later transpires that it wasn't libellous.
POGS You seem to be unaware that sometimes a number of members will report the same post. You also seem to be unaware that posts are not automatically deleted just because someone has reported them. The idea that, say, half a dozen people, plus the Gransnet moderators, plus the author of the reported post should discuss the legal ramifications in detail when, almost certainly, none of them has any formal qualifications for doing so is laughable.
As for other posters wondering why a post has been deleted, does it really matter? In the case of very busy threads, many will have read the post before deletion and are likely to be aware of the reason. In other cases, regular posters will know that it's just Thingy having one of her regular hissy fits or Whatnot having one of her regular bad tempers. Equally it might be because Doo-dah has been having one of her frequent games of baiting Whatsername until Whatsername gets so cross she posts something abusive about Doo-dah which is then deleted. And so on…