^ I think you're both taking that a little too literally. I think what he meant is that they don't want people going into the theatre expecting to see "the" alien (whatever name you call it by.)
Of course fans of the series know the difference (that's why they're fans afterall) between a true prequel --as in a direct narrative setup for the original film-- and a new story, with all new characters, in the same fictional universe, that overlaps in places. To what degree it'll overlap, we'll have to wait and see. We don't even know for sure if that's the same planet, let alone the same ship as in Alien (my money is on "not".) Either way, I think the producers are right not to expect casual audiences to be familiar enough with the material to appreciate the distinction. Hell, it's a thirty-odd year old film, I wouldn't be surprised if the majority of people who go to see this film have never even seen 'Alien'.