I don't think that "we don't need to build more housing" follows from "we have more vacant houses than houseless". It seems like the implicit assumption there i

I don't think that "we don't need to build more housing" follows from "we have more vacant houses than houseless". It seems like the implicit assumption there is we have the ability to move all the houseless to those house, but that sounds really unlikely (albeit an extremely interesting project if it's tried).