Please don't suggest that people should be murdered with drone-launched missiles for making software. Making software is a peaceful act, regardless of what purpose that software serves.
That is not a reasonable position, "peacefully" writing software that you know is to be used to murder and silence other people makes you just as complicit those crimes (definitely an accessory). No better than a getaway driver.
Software is speech (ie protected expression), like writing books.
A getaway driver is involved after the crime is committed. To assign the same level of culpability to a tool-maker would imply that they have the ability to predict the future.
A better example would be a car or firearm manufacturer. How the tool is used is up to the user.
Software doesn't root people's phones, cops and spies do. Someone sent that iMessage, and it wasn't the author of the software.
Speech can be murderous, and more importantly, it can be punishable. Ok, what about if the getaway driver drove him there as well, and explicitly expressed knowledge of the crime that was to occur and refused to abandon the effort upon receipt of such knowledge.
Given where the group is headquartered, I doubt it. That unacknowledged aerial platform will remain firmly planted on the ground until the next defenseless target is chosen.