they had to do a coup with the implicit threat of violence to enforce the new government
OP would do well to pay attention to this bit in particular as (a version of) this basic framework is also how civil rights groups like the suffragettes and the err civil rights movement progressed their struggles. MLK et al were able to be nonviolent because the implicit threat of more radical black nationalist groups existed. without the backing of force nonviolent protest is easy to ignore by those in power, as we’ve seen with every left-leaning protest movement since the collapse of the USSR