Hawey, you're asking why a Marxist-Leninist would defend a leader who does all these things. Let me answer with material reality, instead of liberal morality like these bitch ass niggas like ace often hide behind.
Firstly, under imperialism, stepping down is often a death sentence for the revolution. Stalin didn't step down, neither did Castro. Revolutionary states are not liberal democracies, they are wartime fortresses and these leaders have been elected into these positions. The vanguard's survival is the people's survival. Eritrea is under US sanctions and surrounded by enemies. A 'peaceful transfer of power' would be a coup invitation.
Also, during a war of national survival, trials are a luxury. The G-15 and others were not 'political prisoners', they were factionalists who challenged the vanguard at the worst possible moment. Lenin jailed opponents, so did Stalin, and Mao did as well. Revolution is a battlefield to maintain our hard won independence and to fight off the enemy. The enemy is at the gate, and internal dissent is sabotage.
Any country under existential threat has a requirement of national military service. Eritrea's national service is not 'slavery' at all. The national service is a defense duty when the US is circling with sanctions and Ethiopia is hostile. The Eritrean state is poor because of sanctions, but that doesn’t mean people are still not paid. The soldiers get food, shelter, and the knowledge they defend their homeland.
The enemy uses information warfare to destabilize. The US funds opposition media. The diaspora spreads lies. In a siege, you don't let the enemy broadcast your weaknesses. Stalin controlled the press, and so did Castro. Controlling the flow of factual information is a matter of survival. Emigration is controlled because the state needs its manpower to build and defend. Under siege, you cannot afford a brain drain. Eritrea is not a 'prison' at all, Eritrea is a beleaguered fortress barring the doors.
We cannot measure Eritrea by Western liberal standards designed for peaceful and wealthy nations. Eritrea is not that, we are still a new country. It is a revolutionary state born from war, surviving against empire. Stalin was called a 'tyrant' too but he industrialised the USSR in a decade and defeated Nazism. Isaias has kept Eritrea sovereign while being starved by sanctions. Eritrea needs it’s revolutionary leadership to survive against all odds.