Because he had all but lost the election and the country was freaking out at what was to come. He should left the controls off.Worth remembering that it was Macri who re-introduced the exchange controls near the end of his term, and that they were more stringent that those of the preceding government. During his government, the peso devalued faster than ever - by 500% in 4 years - so it was hardly a 'normal' currency.
If the current government would quit messing with the exchange rates to hide the inflation this would be much worse.
The official peso rate is a fantasy.