Well, compared with the Argentinian currencies, the US$ is still rock solid.
And the idea is not new - these countries already do that:
Ecuador
El Salvador
East Timor (Timor-Leste)
Zimbabwe (though other currencies are also widely used)
British Virgin Islands
Caribbean Netherlands (Bonaire, Sint Eustatius, and Saba)
Turks and Caicos Islands
Zimbabwe (since 2009, due to hyperinflation of its own currency)
But maybe he's just trying not to get assassinated by the CIA.
There is that, too... Wouldn't be the first time.