Apparently there are a lot of people confused about this, but no, Amazon does not have ownership over the Washington Post. Jeff Bezos bought it with his own personal funds using an LLC: https://en.wikipedia.org/wiki/Jeff_Bezos#The_Washington_Post
My instinct is that Evil Man theory is as simplistic (and wrong) as Great Man theory: there's probably some better explanation that this also provides evidence for, that I'm missing.
And I'm sure Jeff Bezos is so pure he'd never use his power over WaPo to help Amazon!/s