Any rant is best treated by FDev as information. Vital information about what is displeasing one or more players.
I think anyone who suggests that anyone who posts a rant should be banned should be banned for seeking to deprive Frontier with vital customer satisfaction information.
White Knights are never anything but trolls. Never, ever forget this FACT.
I disagree with many of the assumptions you make. A rant need solely not be anti-FD, or anti-ED, it can and has been an anti-Doom and Gloom, anti-ED is Dead genre as well. And there is a way of advising FD that a player is displeased with some aspect of the game, a non-rant post for example. One that doesn't denigrate the company, doesn't accuse FD of lying, deceit or incompetence, one that clearly and eloquently expresses the concern of the author. A post like the latter would actually become a discussion, which is far more valuable to FD as a source of information as it would contain not only the authors point of view but of those agreeing and disagreeing with the contents of the post.
As to your FACT, I assume you are of the understanding that no one is allowed to like the game, or at least, no like an opinion you have put forward. I can understand that, but to classify everyone with those labels shows you are not willing to listen to anyone else's opinion which is a shame because even the most rabid, dedicated White Knights have been critical of the game at some stage and they have just as much right to put forward their comment as you or I.
If I was a White Knight as you are describing I would have reported this post and asked for it to be removed, but that would be counter-productive to the premise of these forums.