Well the question would be, who gets to dictate the size/scope of the project and the rate charged to the government? Is any person outside of Apple really qualified to make that claim? It's not open source code, so Apple could make any claim they wanted. Also, who says they would have to put their 'A' players on this? Why not back-burner that with specially hired 'E', and 'F' level developers? Charging $700-$1000/hour might seem high, but on a custom development project may not be too far out of line.

At the end of the day, there really is no way the government will succeed here, you really can't force Apple's developers to do this, as they could just tell the government to go pound sand. The only way they could get it done is through threat of violence/incarceration or by gigantic sums of money. The government can't really argue that Apple with its billions in profits, that their developers' time isn't worth a few billion.