So lets just address this particular claim.

(i)It is true that the Cuban revolution did preside over political trials and executions.

(ii)You're presenting a misleading picture of Che Guevara's role in the trials of the Cuban revolution. Che did preside over some of them but he didn't execute thousands of political prisoners. Research done by official biographies like the one Jon Lee Anderson did in 1997 show he presided over 55 executions. Still not good. But no where near "thousands.

(iii)Distinctions need to be made between Fidel and Raul Castro's roles in the trials of the Cuban Revolution and Che Guevara's. Because Fidel and Raul Castro(especially the latter) where more prone to summary executions. In the case of Che Guevara it was actually the opposite. Che Guevara actually made sure that there was at least due process in the trials he presided over and even barred those with an ideological bias from presiding over the tribunals. He also acquitted several who were put on trial.

(iv)The context of the trials of the Cuban Revolution is important. The came after the overthrow of the Batista regime. Batista's regime was responsible for the murder of up to 20,000 Cubans and committed both crimes against humanity as well as war crimes during the revolutionary war such as the indiscriminate use of napalm and chemical weapons. When Castro came to power he implemented nation wide a policy called "The Law of the Sierra" which established capital punishment for those guilty of war crimes during the Batista era. It was essentially like what the Allies did in the Nuremberg trials after defeating the Nazis and what happened in the Tokyo trials after WWII.

(v)Fidel Castro and the Cuban revolutionaries also presided over those trials because of intense pressure from public opinion. During the revolution Castro had promised to the Cuban public accountability for those guilty of war crimes during the Batista government. Which sets the context for the trials he instituted. These trials of course produced condemnation in America. Now according to research done in the Book "A Century of Revolution: Insurgent and Counter Insurgent Violence in Latin America's Long Cold War" Castro as a gesture to try and maintain good relations with the U.S actually sought to suspend the trials. This produced a negative reaction among sectors of the Cuban public, particularly families of the victims of the Batista regime who carried pictures of both their dead relatives as well as the officials responsible for their deaths. Many even organised protests over that issue. So the injustice for them was letting those people go.

But to your general point about the developing world having different priorities.....there is actually truth to that and Nelson Mandela himself actually said this in an interview he did on American new networks in 1990. He was questioned about his close relationship with Fidel Castro given his struggle for human rights against apartheid. And he said quite bluntly that we are fighting a struggle against one of the worst racial tyrannies and have no time to spend on the internal affairs of Cuba. The fact of the matter is from the Third World's perspective what they saw is this. The U.S and Western governments backing apartheid and many colonial systems. Cuba fighting against apartheid and the colonial systems dominating them. Regardless of Castro's authoritarianism who are they gonna have a higher regard for?