In term of roleplaying, I think we should be able to banish settlers. For story reasons, I can understand you can't banish essential NPCs like Beth and Jerry, but we should be able to banish random settlers just for freedom of choice. It's like maybe our characters are against ghouls, so they want to banish ghouls from their settlement or maybe we just suspect someone for being a synth, we should be able to banish them.