> By definition sabre-rattling means aggressive displays of power.
Which Argentina, particularly by way of its Navy, has been engaging throughout the 2010s over the Falkland Islands.
> Argentina in democracy has continued to assert their sovereign rights over the Malvinas Islands via diplomatic means.
Among other things, enforcing a de facto blockade using naval forces to prevent innocent passage of civilian vessels is -- as well as arguably a violation of the UN Convention on the Law of the Sea -- clear saber rattling, not "diplomatic means".
> You are fully entitled to believe the claim is invalid or wrong, but this that not make it sabre-rattling.
You are fully entitled to believe that the claim is valid or right, but that doesn't change the fact that the Kirchener government has been, for years, engaging in, alongside diplomatic efforts, saber rattling in regards to the Falkland Islands.