In other words if a mill worker's site shutdown and this person now depends solely on UBI I don't see why they should feel like they should afford some place in the closest big city if they don't get a job since their active addition to productivity is nil. If they get a job then they may or may not afford a place in that city. Still, it's not "owed" anyone.
The incentive itself does this. First, there's the "opportunity" of living on the UBI - not a great option but more than there was before. Second, there's the opportunity of meeting the needs of the other people moving to such places, as well as those who lived there before (with their increased ability to pay).
And this leaves aside the fact that an increasing number of opportunities are not inherently tied to location.