Originally Posted by
Heeeere's Olesker!
I would have seen the scenario unwinding as a result of a covert but aggressive move by a major power -- either internally on Eternia or externally, from another planet. There would be skepticism about this and resistance to arm from Randor and Marlena, along with support from The Sorceress who promised peace. MAA would first respectfully lobby for forceful resistance, reminding that The Sorceress has not said the move to peace would be one wihtout bumps along the way.
In the face of insistent pacifism by Randor and Marlena and unqualified belief in The Sorceress' prediction of peace, King and Queen unintentionally weaken the Eternia's ability to resist aggression. Even when Duncan uncovers a plot by their adversaries, Randor and Marlena cling to their pacifism, believing in The Sorceress and drawing further comfort (and false confidence) from Skeletor's absence.
Seeing impending doom for the planet and Randor and Marlena's refusal to gear up for resistance, MAA feels he has no other choice but to perform a coup and save his planet. ('His planet' is intentionally self-centered and a reflection of how Duncan may become slightly corrupt through his subconscious and long and well repressed thirst for power, having lived in others' shadows for so long, thus now referring to Eternia as 'my planet'.)
There were alternative possibilities -- Marlena and Randor falling under mind control or aliens either possessing them or putting duplicates in their place to create the pacifism. But the first scenario seemed to work for me.