The promise of fixed-price contracts is that the contractor is incentivized to get really creative and cut costs in order to maximize profits, like SpaceX has done. SpaceX is charging NASA about $220M per launch of the Falcon 9 -- the same rocket they price on their website for $62M -- and they get to keep the rocket and capsule for reuse too. Now at a marginal cost that's a minimum of 72% profit, and probably much higher. Now if SpaceX botched their demo flight and had to do another, would NASA be willing to pay the cost? No, and they shouldn't: the risk of cutting into their margins is what incentives them to keep on schedule, on budget, and minimize risk.

Yet Boeing has shown consistently that they are only able to operate in the old business model where "profits" disappear into "overhead" and contracts earn only a small margin of profit. Then as something unforeseen happens, as has happened multiple times, they threaten to pull out and force a renegotiation.

This defeats the entire spirit of the fixed-price contract, and costs the taxpayer. IMHO NASA contract officers should call the bluff, and give the contract to Sierra Nevada if Boeing does back out.