You conveniently left out the years and years of litigation, nearly a hundred prior court decisions (all against Argentina, and ignored), dozens of attempts (rebuffed by Argentina) at negotiating a settlement with the holdouts (most of whom do not fall under the pejorative title of buitres), the creation of an Argentine law (cerrojo, still active) prohibiting Argentina from paying the holdouts, and the fact that there was no initial negotiation which led to the canjes -- Néstor Kirchner said Argentina would pay 30 cents on the dollar, take it or leave it, period -- all of which factored into this final, extreme decision by the court.
Your comment blithely suggests that this was some bizarre decision which came out of the blue.
Far from it.
Argentina had years to settle with the holdouts amicably, and on much better terms. The government very deliberately chose not to.
This is the result.