I don't intend to minimize your point, rather I want to point out that if you are saying "don't write unless it's real" you are really truly stepping over what value creative writing provides. Even to disclaimer is to say ignore what was written because it isn't real.
Creative writing for satire or parody are critical aspects of humanity. It is unfortunate when lives are at stake as a result. But there are so many writings in human history that do this - what is your proposition for those?
It wouldn't have been the same, for those of us who thought it was real (I won't lie, I'm one of them.) Whether it was due to not getting that Fizz Buzz is small and wouldn't need a team or that the letter was meant to emphasize the fiction and not hammer home the message (as I thought.) It does no one any good to go and blame the man making the posts for something we failed at (like fact checking, or reading the rest of the comments before commenting myself.)
Yeah it's embarrassing when it happens, take this as a lesson to self improve. Not attempt to call out fake activism.
This is why we have stuff like "All characters appearing in this work are fictitious. Any resemblance to real persons, living or dead, is purely coincidental." in a book about starships and aliens in a far-off galaxy. Not everything needs to be labeled for the lowest common denominator.
All stories are metaphorical, even the true ones. And many of the most honest stories I have read have clearly been fictions.
Perhaps it is attempts at truth telling that should display the clearest warning, as it is generally better to start with the assumption that anything within the realm of normal media is written with an agenda and is probably not entirely true.
As to what counts as fake activism, the claims that were made in the story by raganwald are things that are easily verified as fiction by merely scratching the surface.
Where Mike Daisey actively promoted his work through a journalistic media outlet and only revealed the fabrications after an investigation to trace the interpreter he used in china, this is a post on a blog where as soon as the author is asked, "Is this real?", they write a disclaimer explaining that it isn't, but was written to illustrate a point.
Creative writing for satire or parody are critical aspects of humanity. It is unfortunate when lives are at stake as a result. But there are so many writings in human history that do this - what is your proposition for those?