Rothman is an asshole but I don't think he's directly responsible for some of that stuff. The theatrical version of Kingdom of Heaven, for example, was Scott's own idea, not Rothman's. Scott felt that the film was too long so he himself edited it down. He later regretted doing this.
Anyway, I'm against the idea of an Alien prequel. For one, there's no point. This isn't like X-Men or Batman where we can explore the pasts of the characters. Ripley doesn't really have a story until she fights the Alien in the first film, and revealing the origin of the Alien itself would spoil the mystery.
No, it's Alien 5 or bust.