I have a sneaking suspicion that these guys will be used to stimulate role diversity. Bungie has clearly stated they don't like people being able to become complacent in a niche role (random teleport on Atheon rather than farthest away from Atheon) and these GKs could be used as a way to different members of your team to use the sword. Ex: player 1 uses sword initially; no gatekeeper activity. Next sword run player 1 grabs sword again; gatekeeper descends and begins attacking team forcing sword bearing member to return and kill it or face imminent death. Goodluck dodging a GK while killing boomers/ogres and if anyone does here comes the over soul! Conversely if player 2 were to grab the second sword; gatekeeper remains inactive. And so on until Crota is dead... No repeat sword runners. There are only about 5 swordbearers that spawn before enrage and it only takes about 4 swords when Crota is a level above you (33 v 32) maybe a 5th if you stumble.