The same tech can also walk into a burning building to locate trapped people without endangering the lives of firemen, crawl through rubble to find survivors after an earthquake, power household robots to assist the disabled, and more. I know the source of funding here is distasteful, but this is a dual-use technology if ever I saw one.
It doesn't justify anything. It just shows that we are already killing people in almost every way imaginable so another new one would not be anything all that new.
As long as humanity will want to kill eachother, everything will be used as weapons. Computers are used as weapons (hell would computerized bombs and missiles be possible otherwise?) boats are used to kill people. Airplanes used to kill people. So now robots, why not its the next step. Knowing the US government they will manufature them without any bit of encryption and with a radioshack remote control someone can hijack one of these :P