He said that because it was obvious that the USA would impose an embargo on the island and force most of the world to follow it, it was Castro's fault. He said that if Castro had his people's best interest in heart, he would have caved against american pressure.
Liberals are quick to make victim-blaming, might-makes-right sorts of arguments when it comes to condemning communist countries and left-wing projects in general.
Like when you point out that failed socialist projects in Latin America failed in large part due to intervention from the US, and suddenly their argument becomes "If capitalism isn't superior to communism/socialism, then why was a world superpower and richest nation on earth able to overcome these nations that had been impoverished colonies within the last few decades?", literally the lib version of "If the whites aren't the best race why'd they do the colonizing and the others got colonized?".
That, coupled with their desire to hold and constantly proclaim a moral high-ground, makes them very annoying people.
It's really funny because even a 5 year old could understand the real reason.
It's because resources = power
US = resources
The Americas in general = resources
The Atlantic is literally baby-mode, the Pacific is godmode