I have mixed feelings- by nature I am a curious and inquisitive person, and have an innate desire to discover what is hidden. On the other hand, I like surprises, and, there are certain things that, in regards to this type of scenario, I don't want to know- For instance, we recently had an exciting encounter filled with some hot talk and verbal 'teasing' on a subject that has [so far] been merely fantasy fodder, but afterward Mrs. Twisted felt that she had the need to reassure me that she wouldn't actually enact the particular scenario that had been the subject of the teasing...and that kind of killed the 'hotness' of the scene, if not for the [then] current bit of play, it would kill it in the future because it would now be in the back of my mind that it would never really happen.
Part of the excitement of this sort of play involves the creation/fostering of particular psychological conditions, and (as has been discussed here before) a certain amount of 'suspension of reality' and the 'mind fuck' (to put it slightly crudely). Exposing the KH forum to the view of non-KHs could open them up to criticism from their partners, bring to light insecurities they are trying to keep hidden in order to create a 'better' atmosphere for their partners, and could spoil surprises they might be planning/discussing for the future.
If Mrs. Twisted were participating in the KH forum, I suspect that I would have an even greater desire to put my eye to the keyhole than I do now, and I can see that it is possible that I would either be disappointed at learning something I didn't really want to know, or, I might be tempted to influence her outside of the forum after having seen her discussions with other KHs.
All things considered, the decision of the KHs to expose their thoughts and discussions should be up to the KHs themselves, and that does not require opening the forum to non-KHs. There is nothing to prevent the KHs from opening threads on non-restricted forums in order to inform their partners of what they might want them to know or think (should they choose to make these thoughts/discussions public).
In short, although I might be as curious as any to see the [hidden] discussions of the KHs, objectively I would have to say that I think it shouldn't be permitted.
Just my opinion, for whatever it may be worth.
04/07/19 "And then I 'punished' you by making you lick my pussy after I let my other 'boy' fuck me." --Mrs. Twisted