I get the rule about not posting about derivatives and I agree with it as it is bad manners and it wastes folks time.
If you were a Windows expert would you be happy if folk kept on knocking at your door asking technical questions about GNU/Linux or BSD or having hundreds of e-mails asking about the same. Would you walk in a Lap Dancing Bar and expect to see a Catholic priest about a confessional, of course not you would go to the nearest RC church.Would you look for a 5* holiday at a travel agents who had a big sign outside their door saying "Specialist Holidays In The Frozen Antarctic" of course not if you were a decent reasonably intelligent person.
You may if you were truly stuck, pop your head around the door and ask for directions with a "sorry to bother you, and a , "thanks for the help". Nine times out of ten you would be given some help as most folk do not mind giving a little helping hand to a genuine lost soul. However those poor sad folk who deliberately post about derivatives well they are just sad folk, maybe they will grow up one day and gain some manners and a sense of decency and a life.
As to having a Arch Derivatives section, I do not recon it is a good idea as it would just waste real Archers time. The derivative crowd can always set up their own G+ as it is easy and free or set up their own web site.
Thinking about it , you could have a Arch Derivatives section at the forums with one post as a sticky containing a whole series of links to all the derivative or alternative distro home sites. That way we would still be lending a helping hand without wasting too much time.
As to JuNest well that is a tricky one. To my uneducated barbaric mind it seems to not be a distro as you can only run it in a host to me it is more like a program along the lines of Docker for instance. So if it was made into a AUR package then you could legitimately talk about it on Arch forums. The thing that differentiates it from a derivative to me is that it uses pure Arch packages with additional scripts to help it run, nothing has been changed or altered. It seems to be a very good idea for folk who want to try out new and exiting stuff in a safe manner with tools that they are familiar with.The ability to run it on different distros is a great idea as it gives you the ability to take your favourite toy with you wherever you go.
I am a tad puzzled by the G+ reaction as Evo Lution Q's and plugs are allowed.