If the Argentine authorities could not maintain the stability of the peso, they should not impose restrictions on the purchase of foreign currency. They essentially put their citizens in a hopeless position. It is good that Bitcoin is not controlled by any government agencies. The population can at least exchange the rapidly devaluing peso to Bitcoins.
It is without a doubt a very unfair policy, but once you understand that governments are not in place to help people but instead to keep their power and if possible to increase it then it makes complete sense why they are doing that.
They are imposing those restrictions on the ability of people to obtain foreign currency because if they didn't do that then their currency will crash and they do not want that because if that happened not only that will damage the economy and the honest people of Argentina that will also damage their image to the point it will be impossible for them to remain in power.