It's good to have warning, but you should keep it in perspective. You could just as easily and correctly say
"Violent and sometimes fatal criminal attacks, including armed carjackings, home invasions/burglaries and kidnappings can occur at any time and in any location, particularly in Los Angeles, New York, Chicago and Miami. As recently as spring 2010, U.S. nationals were victims of carjacking and kidnapping. In the short-term, the continued displacement of thousands of people by endemic poverty and the availability of weapons could result in an increase in crime, both petty and violent. US authorities have limited capacity to deter or investigate such acts or prosecute perpetrators."
I spend a good part of each year in Nairobi and feel just as safe as I do in any US city. Enjoy yourself, but be aware of your surroundings. It's a great place.