If cruise-lines will withdraw ships anytime there are incidents, there will be not that many ports left.
Almost 100% of the violence is drugsrelated, almost never is a tourist involved.
Yes unfortunately in Mazatlan a tourist was hurt, but he wasnot a cruise-passenger.
Remember the incidents in the past in Jamaica, St. Thomas, Rome, Barcelona, to name just a few. And at the moment the civil unrest in Egypt, Tunesia, Thailand....
Apart from various shootings (also not against tourists) in the USA and Canada.