Earlier quoted context omitted.
Except your suggestions here ignore that the surplus given by UBI will be amortized into rent and staples costs. It's all well and good until you get into the weeds and realize that a lot of price fixing or pseudo price fixing needs to happen before UBI becomes realistic. If the argument is getting rid of legislative and bureaucratic bloat, it's definitely not quite so easy or quite so effective, choose one.
Why would you expect inflation to occur? As long as UBI is payed for via taxes and not deficit spending than the money supply isn't changing. And as economists say, inflation is a monetary phenomenon. Supply & demand aren't radically changing either. America's poor eat too much, not too little. And while there are homeless people in America, most sleep in shelters. If anything, you might expect the price of the cheap…
If everyone has another x+12,000 dollars, the amount of money available for low income housing has strictly increased. Landlords are then in a position to raise prices proportionally.
The "America's poor eat too much" line is also not strong. You might argue that they eat the wrong things; this is the food desert/education argument that's commonly made. Regardless there is already artificial price fixing of many staple foods like milk and bread, which is a much better argument.