Gold is also a lot more volatile than most currencies, which in turn makes it less suitable as a currency than dollars or euros.

A trait gold shares with bitcoin. The volatility makes it terrible as a currency, not to mention the expected rise in value. That makes BTC even worse as a currency - there is no sane reason to spend bitcoin if you believe in the concept.

And I don't think you're disagreeing with him. I think you're trying to say "well, this other thing that doesn't get used as money anymore also doesn't fit his definition of money" and then implying that this somehow disproves his argument.

When, in fact, it lends support to his argument.