How do you know that that is happening? I have occasionally seen posts over the years that have been accusatory of this sort of thing, but I don't know that there was ever any truth to them.I noticed the decline in posting when the moderator who owns a house there started policing the site and removing posts that said anything negative about Cozumel.
But be that as it may, it wouldn't account for the drop in neutral and positive posts; that just seems like a decline in interest to me. I will, however, keep an eye on yours from today to see if it and my reply disappear.

EDIT: What I have seen is spats between negative posters and some of the rest of us that got so acrimonious that whole threads or sections of them were removed; I don't have a problem with that.