Yeah, I'm hoping he may have misunderstood. Signourney Weaver said they had to wait until Alien Covenant was released before they proceed. I can only assume Blomkamp wanted to reveal things about the Engineers that Scott wants put off until he's told his story first. But hopefully whatever that is is told in Covenant alone and not the next three combined. The likes of Michael Biehn and Sigourney Weaver will be in their 70's by the time all three Covenant prequels are done.