Until now, the government of Argentina has abused its currency monopoly by printing money, with devastating consequences. Inflation is approaching 150% per year. By "We'll abolish legal tender, stripping control from the state", GP means "We'll abolish legal tender, eliminating the government's currency monopoly and allowing the people to choose a sound currency." This is, by definition, "stripping control from the state", where "the state" obviously refers to the Argentine government.
> it's giving it to a sovereign state that doesn't have your interests in mind.
This would be true if the Argentine government was imposing the dollar as legal tender, but they're not. They're allowing the people their choice of currency. For now, that may well be the dollar. But if the US government begins to abuse the dollar (via inflationary policies, for example), dollars will lose favor and a more sound currency will take its place.
This also prevents the Argentine government from steering their economy with monetary policy, but Libertarians view this as a feature rather than a bug.
With devastating consequences for the middle class.
It's printing money to keep entitlements for the poor and to keep the rich from paying for those entitlements (more than they already are).
Does Argentina even have a middle class anymore?
I was looking at wealth inequality - and to be in the top 10% in Argentina - you need barely more than $100k.
It seems like, historically, a decent chunk of the top 10% wouldn't even count as middle class in Argentina right now.
Choosing the dollar isn't "stripping control" from the state, it's giving it to a sovereign state that doesn't have your interests in mind. Given the current situation it may be better, but lets stay in reality here.