I think that is a bummer just because they were fun to use on Patrol but if I am working on the "Kill Hive Sword Bearers" bounty I always use the "Fist of Crota" mission on Earth (I think that is what it is called?). Just start the mission, run past Omnigul and kill the Sword bearer that spawns. Head back to orbit and repeat. takes about 10 minutes and is much faster than waiting for them to show up on patrols.