(Comments like this make me want to stop reading Hacker News.) Just because the "gunpowder" is expensive doesn't stop the production of containment vessels or delivery mechanisms:
http://articles.sfgate.com/2004-10-04/news/17447495_1_antima...
http://en.wikipedia.org/wiki/Antimatter_weapon
Additionally, "antimatter" can include positrons, which are much cheaper to produce than antiprotons.
My advisor also worked on creating antimatter traps at government labs, but none of the projects had any kind of defense related purposes.
Your advisor may not have been involved in all imaginable projects related to antimatter.
There are only a handful of interesting research questions about antimatter that exist at reasonable scales. Most of those are either fundamental physics or medical in nature.
Along with research into directly producing weapons, antimatter can also be used to initiate (micro)fusion, and has been researched for space travel: http://en.wikipedia.org/wiki/Antimatter_catalyzed_nuclear_pu...