Ok, so I saw this thread and decided to do as much research as 20+ minutes on Wikipedia can provide and I believe I've got a few ideas that are neither wildly outlandish or completely off the mark of the political realities that existed and continue to exist in Equatorial Guinea.
Since Francisco Macias's election in 1968, there has not been a single free election in the country since. He had been the son of a chief who was murdered by a Spanish colonial official and was orphaned, but eventually grew up to be a Mayor and later Deputy Leader of Parliament, all under the continued colonial status of the country. The same year that ended, he won the election and then declared himself President for Life, executed all major political opponents and maintained power for about a decade before being executed by firing squad in 1979.
Okay, so that's a pretty dark series of events and there's a little of easy contrasts that can be made between him and Atanasio Ndongo.
Atanasio Ndongo was a writer and musician and political figure in exile operating out of the neighboring nation of Gabon. Antanasio Ndongo's role within the history of Equatorial Guinea is extremely interesting. He wrote the national anthem and had established a political party in favor of the liberation of Equatorial Guinea 9 years before it gained independence. When it did, he returned to his home country, ran for president, and lost. He was then appointed as foreign minister for the country, plotted a coup, and was then executed.
Now, I do not wish to paint Macias as a villain or Ndongo as a hero and I will try my hardest to avoid that. It's very easy to trace a line through the notable events of Macias's life and assume that his violence had its roots in his upbringing in a harsh colonial system, where his father held a position of considerable authority and respect, but was still casually murdered by a Spanish official for simply making a request. He eventually began to thrive under this system, gaining increasing governmental powers and authority until he was president, beyond dispute, and saw enemies everywhere. He executed numerous political rivals and opponents, he cancelled all elections after his own, and he became a brutal dictator who met a violent end.
Ndongo was an artist, he was a committed activist, and, despite having lost the election, was still popular enough to be placed in an important cabinet position. This does not mean he would have been a saint or the founding leader of a young republic in Africa, but, hell, he could have been. I much prefer the idea of the 1968 election going the other way. Ndongo peacefully achieving power and Macias conceding would probably have been a much better situation. I cannot pretend to know Ndongo's politics based off of the little bit of information readily available to me, but if he were a committed republican and Macias became an active parliamentary opponent, then that could be the beginnings of a healthy democracy by today.
A coup though? A coup would cost Ndongo all of the political good will that would be given to him in an electoral victory. He could be the most committed republican and the most wonderful writer and musician in the world, but the moment he seizes power by force is the moment everybody should be skeptical about his intentions. Even if he did it for some supposed altruistic reasons. Maybe the coup was instigated over the multiple, awful moves Macias was making to establish himself as President for Life and the dictator of Equatorial Guinea. Maybe it wasn't and it was just over their political differences. I do not know, but I have my doubts that things were so straightforward.
Looking at the other contender for the 1968 Presidential Election, Bonifacio Ondo Edu, I see somebody who seems as though they were committed to the democratic process. Edu was the Leader of Parliament who Macias was the Deputy to. Edu ran the election and the results came back with him losing. He willingly, peacefully surrendered power to Macias. He would definitely be committed to a democratic process if he had won the presidency, and maybe that was the norm among the political elites of Equatorial Guinea in 1968-69 and Macias was the outlier who did not believe the institutions should have the power, but that rather he should. I hope somebody more knowledgeable can give some answers. I tried to pose as many as I could to create possible discussion, so please, if you know literally anything about this time in this country, say something.