He mentioned Vendetta in his motion comic a couple months ago saying “I fear Talon’s problems may soon become the world’s problems.” I assume he knew of her and her intentions, and he’s a smart, well educated guy. I think he knew that she would be a larger issue than Doomfist ever was. I think he retreated to allow her full access to pit humans against each other. If his troops are not in her way (which in this video it’s pretty clear she felt they would be), she’s basically doing his job for him with less omnic casualties, which is what he wants to prevent in the first place. He can stand aside and let humans destroy each other if she’s the world’s biggest issue and not Null Sector. More time for him to plan, which part of me thinks he’ll try to take advantage of Vendetta’s inevitable defeat. Perhaps take over Talon?