> So, Where do we draw the line between a company rightfully refusing to host inappropriate content and a company "abusing" its network effects?.

I don't think the app description of Gab is an appropriate content. Google seems to assume that the content of the Gab app will be innapropriate. Given this is about freedom of speech I'm not sure they should be the one deciding this. Are they also removing Gab from their Google Search results?