I think people struggle with the fact that it's not a legally so. However, per the article, Bezos is exerting power over WP because Amazon lost contracts to Microsoft (due to WP being critical of Trump). Their balance sheets may not be aligned, but their interests are.
And if Bezos toes the line and does things that Trump likes, then Amazon may benefit.
Trump sees "friends" and "enemies" [0], and doesn't care about actual ownership of shares. "Bezos is a friend and sorted out that WaPo mess, so I'll cut him some slack and kill off that Amazon anti-trust thing" is something we can all picture Trump saying.
[0] Obviously I have no idea what he actually sees or thinks, but this picture seems to match his public pronouncements.
