I think Ven Nanananda answers that quite well, in a very similar way to the commentaries.retrofuturist wrote: That being so, why would it be any different if they were not to die right there on the spot? If there's no basis for vipaka at death, what basis is there for vipaka in the arahant's life? What is the difference, and what is the reason for it?
http://www.beyondthenet.net/calm/nibbana18.htm" onclick="window.open(this.href);return false;
From the particular context in which the verse occurs, it seems that this imagery of the fire is a restatement of the image of the lotus unsmeared by water. Though the embers are still smouldering, to the extent that they are no longer hungering for more fuel and are not emitting flames, they may as well be reckoned as `extinguished'.
We can draw a parallel between this statement and the definition of sa-upàdisesà Nibbànadhàtu already quoted. As a full-fledged arahant, he still experiences likes and dislikes and pleasures and pains, owing to the fact that his five sense-faculties are intact.
The assertion made by the phrase beginning with tassa tiññhanteva pa¤cindriyàni yesaü avighàtattà ... , "his five senses do exist, owing to the non-destruction of which ...", rather apologetically brings out the limitations of the living arahant. It is reminiscent of those smouldering embers in the imagery of the Nàgasutta. However, in so far as flames of lust, hate and delusion are quenched in him, it comes to be called sa-upàdisesà Nibbànadhàtu, even as in the case of those smouldering embers.
This cooling off happens just before death, without igniting another spark of life. When Màra comes to grab and seize, the arahant lets go. The pain of death with which Màra teases his hapless victim and lures him into another existence, becomes ineffective in the case of the arahant. As he has already gone through the supramundane experience of deathlessness, in the arahattaphalasamàdhi, death loses its sting when at last it comes. The influx-free deliverance of the mind and the influx-free deliverance through wisdom enable him to cool down all feelings in a way that baffles Màra.
So the arahant lets go of his body, experiencing ambrosial deathlessness. As in the case of Venerable Dabba Mallaputta, he would sometimes cremate his own body without leaving any ashes. Outwardly it might appear as an act of self-immolation, which indeed is painful. But this is not so. Using his jhànic powers, he simply employs the internal fire element to cremate the body he has already discarded.
This, then, is the Buddha's extraordinary solution to the problem of overcoming death, a solution that completely outwits Màra.