A lot have added a DIY tailgate lock. Some have purchased an after market option...
http://www.ridgelineownersclub.com/...popular-demand-10-electric-tailgate-lock.html
2005-2015 Honda Ridgeline Smart Lock Combination Tailgate Lock- Black
Honda Ridgeline Automatic Tailgate Lock [HRFS06C] - $124.99 : Dynolock Products, Secure Your Tailgate.
http://www.ridgelineownersclub.com/...popular-demand-10-electric-tailgate-lock.html
2005-2015 Honda Ridgeline Smart Lock Combination Tailgate Lock- Black
Honda Ridgeline Automatic Tailgate Lock [HRFS06C] - $124.99 : Dynolock Products, Secure Your Tailgate.