While this may be true (although I wouldn't be surprised if nobody actually collects data on the number of people killed by falling coconuts), I'm not sure of its relevance to the general question of whether gun control is a good idea or not.
It's relevant because usually sane logical people throw both out the window during this discussion.
Distracted driving kills umpteen thousand drivers per year. We legislate against cell phone usage in cars. WE DON'T BAN CELL PHONES. Shit, we don't even MANDATE the installation of apps that would render them useless in a moving vehicle.
Tens of thousands drown in backyard pools. We legislate that pools must be fenced in and reasonable precaution must be taken to secure your pool. WE DON'T BAN POOLS.
Get my drift yet?
Things in life are dangerous. Things in life are misused. Things in life kill people. However, our first response is to say, "that's a real shame" when someone gets killed by a coconut in Fiji (there are stats, btw and in 2012, more people were killed by falling coconuts globally, than were killed by "rifles" in the US)--or drowns--or texts themselves off the road--or drives drunk.
But when a totally deranged loon shoots two previous co-workers, we say, "BAN GUNSSSSSSSSSSSSSSSSSSSSSS" "WHY DO YOU NEED A GUN THAT HOLDS MORE THAN 5 ROUNDS? DEER DON'T SHOOT BACK"