Saavik further confuses the issue by suggesting that the use of "unethical" protomatter had something to do with it. That I think should be considered a totally separate issue. Perhaps use of protomatter kills kittens or something, and David thus should fry for that. But use of protomatter had nothing to do with the deaths that Saavik mentions.
Strange thing is, I always took Saavik's comment to indicate that without David taking a "short-cut" by using protomatter, Genesis would never have reached the testing stage (or at least not for some considerable time), therefore Reliant would not have been assigned at that time for the search for a suitable test-planet, and not fallen into Khan's hands.
She was perhaps judging him unfairly, certainly there's no way that he could have possibly known that his rush for results would have led to TWOK. It's a little like blaming the construction workers of the Titanic for her hitting an iceberg.
I interpret Saavik's comments to mean not that David should have known what would transpire once the project was finished but that his haste to finish the project by questionable means suggests he didn't fully understand the responsibility he was assuming for such a project in the first place, hence her rhetorical questions about the number of people who have died for his impatience. In other words, a more responsible scientist would have waited until a more suitable solution presented itself instead of using an unstable chemical compound in a rush to complete a project, to say nothing of the project's potential itself.