I see your point.
How many lives would you estimate are lost/saved because of what OS is being used?
Wouldn't any vendor have a "military" version of whatever OS they would use anyway? Which would make it a lot safer to use..
The NSA probably cracks as many windows machines as they do Linux/Unix all over the world, I would think that it's all the same if you know where to go and what to do to get in.