Except this has been contradicted by the logic of the technique itself. His intangibility is just an extension of his warping; whichever part is about to get hit goes into the Kamui dimension. Thus, if his entire body is covered, his entire body is in the Kamui dimension. At that point, he's already warped into the Kamui dimension via the intangibility.
The question becomes; if he's already completely warped there, why doesn't he warp out somewhere else?
I understand Kishi's explanation, it just doesn't hold up.
You some kind of idiot? Tobi can only use one of the abilities at a time, the intangibility, or the warp. If he wants to warp, he has to cancel the intangibility, and then warp! Common sense!
He can't warp while he's intangible because, obviously, he has to cancel the intangibility before he can activate the warp jutsu. If he cancels the intangibility, he get's blown to pieces before he can complete the warp, but if he stays intangible, he can only do so for five minutes, and the explosion lasted ten minutes. Again, COMMON SENSE!