You are totally missing the point. It's about increasing that chance before it would normally occur. If you put up a building and decide to cut corners and use substandard materials which aren't up to code. You have increased the risk of death or serious injury occuring should an event like a fire occur. The colonist DIDN'T choose to seetle on a planmet without access to 24th Century technology. That decision was forced upon them. As there was a deliberate act on the part of Alixus to do so, that's what changes it. The vast majority of the colonist WEREN'T followers of Alixus. Just because she was the de facto colony leader doesn't mean they were followers. If she had collected togther a group of people who wanted to live without technology and accepted those risks it would be a diiferent story. She forced her own viewpoint onto others, through acts of sabotage, helped create the duonetic field. She could easily have deactivated it any time, and perahps saved some lives because without it the medical gear they took would work. They could have sent out a distress call which starfleet could respond to. It was no accident that the colony ship crash landed there, Alixus took conscience and dilberate decions to ensure that it did. It is because of those actions that it becomes murder rather manslaughter.