'Oh grow up. Massa couldn't possibly have seen the yellow until after the final turn since it was only waving in a partially obstructed place after the exit.'
Errm.... that's exactly what I was trying to show. which is why I also show that there's actually a green flag waving at the time Massa passed it.
Not you, the OP
Look you guys, aside form the confusion with the flags (Yellows and greens being shown, yellow one waved in semi-obscured position), there was no danger on the track, Sato was well out of harm's way by then and slowing down onto the straight is in itself a hazard - there were no flags before or during the final turn warning oncoming traffic of the hazard, so they would have been surprised by a slow moving Massa.

The Frome Flyer: Smoother, Smarter, Calmer,
Winner.
Jenson Button: Professor, Chauffeur, World Champion Racing Driver.