I presume by Fed you mean the not-government 'federal reserve' which is a contractor to Congress which tinkers with monetary policy and sets the price of money. Federal Reserve quietly provided bailouts to Europe in 2008.
New York Times article,
'“an open facility where European banks could come and get dollars.”
So began what would become the biggest United States government bailout that most people do not know anything about.'
Argentina or Panama having a bit of an economic slowdown whilst the US is growing nicely isn't the Fed's problem: the monetary policy decisions will only take into account to the monetary policy needs of the US, and it's not particularly in the interests of the Fed to bail out Argentine bank reserve shortfalls unless the contagion is likely to hit the Us either.
this needs to be repeated. USD is already the way of doing business in the ARG, and this is essentially just calling it what it is.
this is also seen as a way to stabilize the back-and-forth economic choices that make the currency terrible.
makes sense in theory, but they're an export economy, and a strong USD will make it hard sell beef and mining products.
Pro-Euro: Euro already is controlled by a wider range of countries and there is some incentive to match monetary policy to accommodate those wider circumstances. So a policy is less likely to just support a single countries unique situation and conflict with Argentina's situation.
Pro-USD: USD is already more widespread in South America and actively being used in Argentina right now. This advantage is very practical and concrete right now and trump's all else