James Horner thought he’d have six weeks to write
    the musical score. Instead, he had three weeks,
    and had to write some parts overnight. The movie
    was behind schedule, not even finished being
    filmed (let alone edited) when Horner arrived in
    England. What’s more, the recording studio he’d
    been provided with was outmoded, not equipped to
    handle the synthesizers he wanted to use. Horner
    called the experience a “nightmare,” and ended up
    writing the climactic musical cue overnight.
    Coming away with the impression that a James
    Cameron film was too stressful and rushed, he
    figured he’d never work with the director again.
    And he didn’t ... until Cameron approached him for
    Titanic. (That rushed Aliens score earned Horner
    an Oscar nomination, by the way.)

Some of my worst work has been done in the same conditions though, especially with regard to "technical debt" though I suppose that doesn't apply to the processes in film making as future maintenance is much less of a concern.

To me, this completely clarifies his conflict with Ridley Scott. The director doesn't care at all about #2. And yes, Scott is right: no one is as close to the film as the director and editor. It's not their job to pad the composer's portfolio, although ironically it seems the composers are rewarded for this "tight coupling" that they strive to avoid.

p.s., I never saw Alien, but I liked the OP and I am a Jerry Goldsmith fan from the Star Trek scores, which I used to love listening to on CD. It seems he was happier with those collaborations because he was allowed to express the "romantic" view that he had of human space exploration.