A point pertinent to this series, starting about five minutes into the episode, is where Kirk, Spock, and Bones are encountered by these "Children." A sentry fires a warning shot at them, and we soon see more sentries emerge carrying traditional-configuration bolt-action hunting rifles.
1. The non-military nature of the arms (government forces were seen with submachine guns) would be in keeping with the beliefs of some Essenes of the first century AD/CE about such matters--not pacifist, but non-militant.
2. Such uber-fudd arms, though far from ideal even by TDF standards, can serve a role in such matters.
3. Those armed with them got the drop on three trained Starfleet officers with phasers.
No, such arms are NOT the ideal in 2A or RKBA. But you use what you can get. And those "Children" did.