Shit, I'd go so far as to say that he personally didn't care about anything outside of 'Alien' (and perhaps not even that, given how Prometheus retcons it - and Ridley Scott would be the first to admit that, too).
Any references we got to 'Aliens' were likely things put there by the writer and whatnot that slipped under his radar or otherwise didn't bother him, not conscious decisions on Scott's part.