Well, I think it might be more complicated than explaining it. The rest of the episode doesn't feature Star Trek - like ships with futuristic tech. It's just more modern-looking technology. But since the rest of the show takes place on Earth, it's possible that technology is better there and people have more access.
But honestly I think the in-universe explanation is that the Weyland-Yutani ships shown in Alien and Alien: Earth are blue collar scavenger ships. It would be like aliens finding a fishing boat made in the 90s and assuming that's how technologically advanced we are.
To me, I just liked that they went out of their way to completely re-create the aesthetic of Alien for this. I don't think the rest of the episode abandons the aesthetic at all, but it secures the 70s aesthetic, at least for this portion of the universe, as how things look. They could've easily reimagined how people look or act or how the ship looks and operates. But they didn't.
Again, I assume the juice isn't worth the squeeze if the whole show took place on a ship (it doesn't). But for that section of the show, I liked the respect for continuity.
*******
Okay so I finished Dexter: Original Sin. I really liked it. The show absolutely takes liberties with continuity with characters' ages being off, people joining the police force earlier than they were supposed to, things happening differently than they were originally explained, etc.
But I think there are two reasons I'm okay with that:
1. Dexter is our narrator - modern Dexter - and, while there has never been any evidence that he's an unreliable narrator, he's still a psychopathic serial killer. So if an unreliable narrator explains things two different ways, that's not a huge deal to me (think the Joker in the Dark Knight). There's also the fact that Dexter is, canonically, retelling his origin story to the "audience" as his life passes before his eyes as he believes he's dying (at the end of New Blood). So even if Dexter is a reliable narrator, maybe his brain isn't functioning properly
2. The show is just a lot of fun. I tried to explain to my wife that the show isn't scary at all. The concept of Dexter is dark, but I don't even know how violent Dexter is. Some of the people he kills are violent, but Dexter usually stabs his victims one time in the chest with a big knife. There's blood, but it's usually captured by the plastic wrap that Dexter uses to contain his crime scenes. He chops up the bodies, but either I'm completely desensitized by it, or it's shot in a way that isn't gory. I don't like torture porn, and I'm skittish at stuff like Saw so I don't think it's the former.
But Dexter is a charming guy, the side characters are all interesting, and Dexter never tries to convince the audience that he's not a monster. He's just a monster who is doing good in the world. I think you can root for Dexter to keep doing what he's doing since he's getting rid of worse people, but I don't think Dexter even wants you to like him as an audience member.
I'm going to try and show my wife the original series. I'll let you know if she likes it.