Even the phrasing grates at me. Killing a bunch of innocent people in another country is just a "risk" to some moron with a drone. If all of a sudden that moron was piloting a drone IN THE US and blew up a church/school on accident, I guarantee you wouldn't be so comfortable abstracting away lives as "risk".
By the way, if we count all the innocent people killed by the US as "mistakes", it is certain that number would be >10x the people who died to Islamic terrorists on 9/11... so isn't the US military as much of a terrorist?
Its a sick strain of sociopathic paternalism by which you can abstract away peoples lives as long as they aren't your own countrymen.
I wouldn't be happy about it. But these things are inevitable consequences of war. People get shot accidentally by the police, here, in the United States. We try our best to minimize it, but it happens. It is an inevitable consequence of law enforcement. If one of my family members were accidentally killed by a cop, I would be upset. I'd want to understand the specifics of the incident, and see if perhaps the cop was being negligent in some way. But, if they were not being negligent and the situation had warranted it, and it was just an unfortunate accident, then I would not be angry with the officer, or the department.