Hmmm... I see that you should have an outline for your project, a storyline if it is a story you want to tell, and if you are filling your story with emotions of your characters, it can gets tacky/cheesy very fast and go bad, but... He got offered that job a short time ago and had no real chance to think about a drawn out storyline. My guess is, that he resorts to thinking about it in an organic way, come up with ideas for the next chapter and gets ideas for the whole storyline on the side this way. Surly not the optimal way to do it, but he has been asked to deliver. And him to deliver is what his company promised to the client. He is even on a good way to deliver those first two chapters. The chapters with the highest work amount, I imagine, as you aren't really in the flow to draw the characters, as they are new to you.
While her point of critic might be fitting later on, in case the story really isn't going anywhere, he is just working on the chapters 1 and 2 right now. She is so fucking full of herself, that she doesn't care, that she makes such an obvious attempt at sabotaging MC. It is so superficial, even a noob-editor or noob-manager at her own company could see that. And she already bumped heads with her boss about this matter. That boss better should be alerted by that and take a look into this, as MC isn't providing any good stuff with her as an editor.
Also taking jabs a your worker's selfesteem is only good if you want to lower their salary. You never increase the quality or amount of work they deliver this way. It is so obvious she wants to get rid of him for any onlooker.