"But it's even more useful to keep them alive," Harvey countered. "Dead people are completely useless, unless you need a shield. And even then, they're so messy that it's hardly worth it."

Truth to say, Harvey doesn't really have experience with getting people killed -- his only job is to keep John alive. Everyone else might be expendable to him, but not to John. And if John really wants to save someone, well, Harvey has to work with him.