That's a little overblown. The Genarmeria have ranks and uniforms similar to a military unit, but they are seperate from the Argentinian Army and their missions are distinct. The Gendarmeria are more like Customs & Borders combined with state police in the US. I've never heard Argentinians dysparaging the Gendarmeria, and I've heard quite a few wish they'd replace the provincial police on BA with the Gendarmeria.
The whole thing in Mendoza sounds pretty scetchy, but it appears to me that its judicial corruption and political fighting in which one side entangled the Gendarmeria. They do have some weird jurisdictions down here, so I'm not sure whether or not enforcing court orders in Mendoza is typically within the range of duties of the Gendarmeria, up here in the north they mostly handle law enforcement, traffic control, and smuggling interdiction outside of the major cities but they do have some responsibility for investigating 'economic crimes' too. See
http://es.wikipedia.org/wiki/Gendarmería_Nacional_Argentina &
http://www.gendarmeria.gov.ar/.
The mess between the Kirchner's and the media moguls fascinates me. Its hard to have sympathy for Clarin considering thier own history of political and economic shenanigans. Not that I'm impressed with the Kirchners. I guess Argentina shows what's even worse than a two-political party system like what the USA has: a single party the completely controls the government.