I don't think so. It's about the price of money. If you can buy money for rate a, and sell that money elsewhere for rate b, where a < b, then it's arbitrage on the price of money.
(Where price of money is a synonym for interest rate.)
Gold is not the same as USD. It is a different asset to USD, and carries different risks.
The Greek Bonds you mention, you also consider 'money'. Well, not all 'money' is the same. That's why you get paid more if you buy Greek bonds than if you buy German Bonds, to the same Euro value: risk premium.
Its not arbitrage if you are just being paid for taking on risk, by definition.
I wrote my post, presuming anyone who might follow such a strategy was sophisticated enough to understand what risk is. Risk can be hedged. Risk can also be calculated.
You're right that gold is not the same as USD. It is less risky.
You'd do well to not tell me what I believe about various asset classes, especially when it is clear you have not even read the original comment I made.
By definition, people engaging in arbitrage are being paid to take the risk that the arbitrage might fail. The idea that there is such a thing as a risk-free form of property is fallacious.
Thus your arbitrary demand that I be talking about something risk free is an impossible standard (and quite off the point... but then, maybe derailing the possibility of sophisticated financial discussion was your goal?)
I mentioned hedging risk, and everything else you've brought up in my original comment.
(Where price of money is a synonym for interest rate.)