I would suggest that it is both, as I don't think the two are mutually exclusive, and with the way commodity and currency exchanges operate the lines are definitely blurred.

As for your particular examples; commodities have always been used as a means of purchase whether by way of trade, barter or as a currency substitute (gold, silver, etc). The trade of commodities are protected by law. And currency volatility ranges with some currencies being highly stable and others hugely volatile, more so than most commodities.

So trying to bucket bitcoin like this doesn't seem to be worthwhile. I think the better discussion would be whether or not bitcoin should actually hold any value.