"Hard money" is a commodity that is 1) durable 2) divisable and 3) difficult to fake and 4) difficult to produce.
So bitcoins are even harder money than gold is. They verify all conditions, and even better than gold. It's harder to fake, will become impossible to produce after reaching the 21 million limit, and it's more divisible.
Bitcoins are no more a commodity than US Federal Reserve Notes are, and nor are they backed by any fixed commodity standard.