Responses

In apocalyptic world, being in prison means dieing and suffering slowly. They won't provide them food since it's reserve for those who contribute to the town. This maybe a quick death with less suffering (but ultimately, what the fck?!?)
I think banishing them from town was a good option, but the likeliness of them joining a different group and getting revenge to the town is high.
They couldn’t make a makeshift prison instead? That’s a harsh ass punishment. Dude’s the Negan of BL