As the third reviewer, I am prepared to clarify my reasons. Frankly, the tag as written and edited was OK for anyone without any depth of background knowledge of the concept of a hollow earth. Basically, it was adequate, though slightly misleading, and needed improvement.
About improvement, the tag review doesn't allow for comments or suggestions to edit it for improvement. What choice I did have? (a) I could have approved your tag then gone back and edited, or (b) rejected it because, in my opinion, it needed to be improved.
Obviously I chose (a). Now I sympathize with Zxyrra for feeling aggrieved. If I was in his circumstances I would feel so too. Perhaps, more so, and with more justification.
Why you may ask? Because I have read and own a copy of David Standish excellent popular history on the subject.
David Standish, Hollow Earth: The Long and Curious History of Imagining Strange Lands, Fantastical Creatures, Advanced Civilizations, and Marvellous Machines Below the Earth's Surface (Cambridge, MA; Da Capo Press, 2006).
The hollow earth concept has only been added to conspiracy theories in fairly recent times. Roughly, late twentieth century, but prior to that has mainly had a reasonably long history as a piece of pseudoscientific nonsense and the stuff of fantastic adventure romance novels like those of Edgar Rice Burroughs. Originally, it was proposed as a scientific hypothesis by Edmund Halley, no less, for the nature of the interior of planet Earth. (That's right, Mr Comet himself.) Since little was known at that time, this was a reasonable hypothesis to make. If Physical Review had been published back then, it would have easily been published in that august publication.
Sorry, Zxyrra, the weight of history is on my side. The conspiracy theory twaddle is only in current fashion, but it didn't start out as a conspiracy theory. Those wackos have recently abducted it in their Swastikaed flying saucers. My dilemma was whether I should let your tag go through and do an edit myself or give all too brief reasons suggesting, inadequately, where improvement was needed. I recognize the failings and inadequacies of the latter. I acknowledge you were doing the best your could with the knowledge and resources available.
Standish's Hollow Earth is great read. There a lot of fascinating stuff in there including the early history of polar exploration, and he is sympathetic to many of the addle-minded folk who, over time, have embraced various versions of the hollow earth.