I know the Editor's comments are usually done with a sense of humor, but this time it sounds like maybe it wasn't meant in a joking way. Which is fine. BUT, if the Editor was serious, then I have to respond, because I think I can give the answer to his/her concern... The Editor wrote, "I'm sorry, but I have to challenge the assumption implicit in this concept. If a humanoid merely crouching atop the Tardis would likewise be transported through time, what about the pavement the Tardis is standing on? What about the air surrounding it?"
First off, I agree with your concern. I don't think that would be possible either. Okay, but, here's the thing: this is just a picture of the Tardis... SOMEWHERE. There's nothing to say that it is, at the moment captured here, traveling through the vortex. It could be anywhere. I think you've made the assumption that it's traveling through time in this picture. The picture doesn't imply it, in my opinion. Now, MAYBE the halo of light around it is supposed to be the vortex... I dunno. But to me, it doesn't look so much like the vortex. Maybe I'm wrong, but I don't see it like that. There are any number of things that could more likely cause that kind of light, instead of the vortex. So, if you want an explanation for this "fatal flaw", then I'd have to say... he's not moving through time at all. He could just be hovering in front of a bright light on a foggy night. It could be anything.
And consider this... if it is your sincere belief that a humanoid on top of the Tardis absolutely COULD NOT be transported through time... then certainly he's not moving through time here... BECAUSE... there's a humanoid on top of the Tardis, which is not possible. Right? Therefore, this MUST be some other scenario.
Me, I love this design, and I'm ordering mine right now. :D