It appears there are two discrepancies. First, Dr. Rubilar is saying Decree 616/2010 is contrary to the Constitution. In other words, if Cristina wanted to alter the immigration law in accordance with Decree 616/2010, she needed to change the National Constitution.616/2010.
Simple. The National Constitution allows you to enter the country in anyway. The immigration law and the decree is unconstitutional.
Second, Articulo 24(a) says nothing about leaving the country and receiving a 90-day extension. If I understand Dr. Rubilar correctly, the 90-day extension is simply a practice - it has no base in law. Therefore, travelers who depart Argentina in order to receive another 90 days in Argentina are out of compliance with both the National Constitution and Decree 616/2010.
Would someone corroborate this?