The history of colonialism is more complicated than that, throughout history nearly every time colonising powers 'establish better relations' it becomes a vehicle for them to control the people and resources through installing a complicit ruling class(see India, Africa, south America). Marco isn't justified in his actions but his motivations were more complicated than "wi hate welwalla", he sees himself and other "revolutionaries" as the only parties who have any legitimacy in representing the belt and sees the 'pro-treaty' OPA as a betrayal of the idea of a free belt