I don't know this specific area but the idea that American (or Aussie, whatever) tourists are hands off for cartel violence is patently false. It's probably mostly true IF an area isn't being contested at all between rival cartels. If one has an area locked down, it's likely accurate to say they want absolutely zero heat brought down on them because of tourists getting hurt or killed or kidnapped.
But I remember reading an article that said in contested territories, kidnapping tourists etc is absolutely a strategy used to bring chaos and heat. The cartel making a run at the top dog in the area knows the heat will be directed at them, so they do shit to force the government to intervene. This weakens the controlling cartel the most, potentially creating the vacuum they hope to fill and take over that area.
In short, plenty of safer places to visit that offer the same weather, amenities, etc.