The accident was behind the leaders --- throwing a yellow wouldn't have prevented one more car from crashing. There was no jeopardizing of drivers behind the two leaders because they were already wrecking anyway. Nothing would have changed this fact.
NASCAR, for once, done the right thing by letting Harvick and Martin settle it out with a race to the stripe. Can you IMAGINE the backlash they would have got if they threw the yellow flag when they started crashing? Then, remember, we would have to go back to the previous scoring loop. That scoring loop is invisible to you and I. With NASCAR letting those two race back to the stripe every single one of us could actually see for ourselves who won the race. If they would have reverted to an imaginary line that none of us could see then we'd all be arguing who actually won the race. This way, it was clear and we got a great finish.
NASCAR is consistent to a degree in holding yellows off on the last lap. Remember the Brickyard race last year when Kasey Kahne had a heck of a crash out of turn two and they let the leaders race back to the flag for the win? I do think they need to write it into the rulebook that if an accident happens on a green/white/checker finish OR just on the last lap of a race that the lead cars race back to the stripe to decide the finish. They done it for 50 years and it didn't get anyone hurt --- so to only do it at the end of races wouldn't be the end of the world.
But, again, I feel they did the right thing by holding the yellow because it didn't put anyone in more danger and it allowed everyone at home to see who won the race with their own eye's. This is NASCAR's biggest race and for it to be decided by an invisible scoring loop we never see would be a huge injustice to everyone that sat through those 202 laps. Just my opinion.....feel free to flame away.