Well, the argument in the article is that basic necessities are priced based on what people can afford. So, if everyone is getting UBI, in theory they could all afford more, and so prices would just go up; bringing everyone back to where they used to be before UBI, but now without the non-UBI based benefits (food stamps, welfare, etc).

But, the article does not provide any evidence (simulations or studies) to back up that claim and, in my opinion, it is not very convincing.