Re: "Weapons that remove meaningful human control from target-and-kill decisions sit on the wrong side of a clear moral line" confuses several issues.  First, it assumes that human control will mean "target-and-kill" decisions will be made morally, but programmed decisions (guided by software) by definition will be indiscriminate.  This is not the case at all - human control can lead to directly to immoral killing (e.g. killing non-combatants), and, equally, software developers can do their best to distinguish combatants from others, err on the side of protecting civilians, etc.

If the argument is that humans will outperform autonomous robots in protecting non-combatants, that is speculative.  The number of non-combatant and "friendly fire" casualties in combat is shockingly high - it is a pretty low bar that the robots will have to clear. 

Like self-driving cars, builders don't need to prove that the car will never make a driving mistake, just that they will make fewer than humans.