What's the difference, from an economic standpoint? The original poster is saying that some people want cheese and other people need cheese, therefore the people who need cheese will not get what they don't need?

There's something absurd in this argument. No one's going to double their cheese consumption, just because they got money "they don't need", and no one is going to starve because the price of cheese went up.

But also, whatever problem we think we are debating here, it exists with or without basic income.

To clarify my point (although from what you wrote I think you got it right):

The argument that "basic needs" prices will rise (which was what my OP gave) because of UBI must be false, since being "basic needs", they already must be provided to anyone anyway.

In any case, even if a big part of the population didn't had access to "basic needs" the argument would be that: "we can't allow them to have those basic needs or else their price will increase to the rest of us". Than that, is morally wrong.

I hope now it is totally clear what I meant above.