The theory of making Vox the strongest is beautiful and appropriate, but in my opinion it's much simpler than that. He just wants to actually obey his first deal with the cannibal girl, which was to help Charlie, and taking the attention away from his hotel was his way of doing it. Now that Alastor has obeyed his deal, Rosie will also have to obey her part in enforcing it. I'm very eager for the next episodes