I guess the Mexican Bureau of Tourism could put a good spin on it by touting, "Visit Puerto Vallarta, you'll be blown away by the experience!"
Seriously, Ron is absolutely correct. It takes a good amount of effort to pull the pin from a grenade which allows the spring loaded lever (or for purists, "Bouchon") to fly up thereby igniting the fuse on the device.
Just the fact that a live grenade was being carried by anyone in a tourist area give me significant pause. And it's only going to get worse until and unless something is done about the horrific violence plaguing our neighbor to the South.
The whole situation is tragic.