What was Burke's plan.. clearly she wasn't interested in a payday, having already killed one.. and flat out refusing to go.. and even confirming that they were going to kill the Alien, not capture and study.. so why even include her??
What do mean a scapgoat, for the Burke guy? It has been a while since I saw it, but I thought he was using her for her knowledge of the xenomorph and was planning on getting rid of her and the others while in stasis.
I initially took his claim at face value. He wanted her to go as a mission advisor to the marines. She was the only person to have ever encountered an alien before. Assuming that LV426 was actually infested, she'd be the most knowledgeable person on the team. And indeed, she proved very valuable in that role (taking over for Gorman who was essentially useless when it came to mission planning and execution). Had Ripley not gone on the mission, all of the Marines would have been killed in the first encounter.
After Burke is able to confirm her story about the alien's existence, and that they are no longer on a "rescue" mission (everyone is dead), he then decides to bring a specimen back to earth to sell to the bio weapons division. Once Ripley discovers his plan and confronts him about it, he tries to bribe her. When she doesn't take the bribe and threatens to expose him, he decides to eliminate her (and the rest of the marines) and simultaneously smuggle an alien back to Earth for the bio-weapons division.
You're overlooking very key evidence - some of which is presented in the director's cut, but since that was first out on LaserDisc ~1992, that's the version that most of us will refer to.
After the inquest, Burke waited a while and then sent a message to LV-426 telling them to investigate the exact location that Ripley mentioned in the inquest.
He didn't warn the colony of potential severe danger, nor did he mention any of the details that Ripley passed along.
When they stopped getting a signal from LV-426, he knew that it could either be a downed transmitter or they could have found Ripley's bad guys.
Since he hadn't warned them of the danger, it was his ass on the line.
Weyland-Yutani wouldn't be pleased with this middle level manager dude losing them a valuable colony, and Burke knew it, so he went into recovery mode.
Clearly when he sent the message he had to consider the possibility that it was real, and so would have planned numerous contingency plan options in that case.
The rest followed... he wanted money and promotions and glory... but since Ripley knew more about them than anybody else and knew what they looked like, it was convenient for him to have her close - he didn't know she was the badass she turned out to be, so he underestimated that her presence would interfere with his specimen recovery options.
Bringing along a very small crew led by the most junior officer he could locate also fit in with his plans... a green officer was much more likely to obey the Company guy than a seasoned veteran.
So she was very much expendable in his mind - from the very outset of inviting her along with.
While Ripley was undergoing psych evaluations and working on the loading dock, Burke was plotting.
This is also consistant with Ripley's mental state back on Earth\spacestation. Her constant nightmares and ptsd did not present her as the formidable badass she was\ could be, so Burke probably though he could manage her whatever they ended up finding.
- Currently watch classic Cinema like Gods of Egypt
I think Burke legitimately wanted her there as an adviser, at first. I think that, once he got there and saw not only the potential for the creature, but the living specimens in statis, he started to think about how he could profit from it.
And once Ripley confronted him about his orders to the colony, she had become a liability; at that point, he saw a way to not only eliminate her and the Marines, but also smuggle back a Xeno.
But what I wonder is, what would he have done about Bishop?
Bishop wouldn't be a problem for Burke. He was governed by Asimov's laws so he couldn't hurt him and probably had to obey his orders. Bishop wasn't present when Burke was exposed so Burke could tell him anything.
I've never felt there was any plausible reason for having Ripley tag along on the mission, and a woman as intelligent as her wouldn't go back to that planet in a million years (her having bad dreams as the reason is just lame two-bit psychology). Her limited knowledge of the alien was all covered in her report and there really isn't that much she could tell them. The crashed ship with the eggs, the facehugger, acid for blood, the chestburster and how it grows quickly to full size and is strong and agile. That's all she knows. She doesn't need to be there to tell them that and a civilian on such a mission would undoubtedly just get in the way and be an additional liability for the marines.
However, as with all the Alien sequels, they needed a convenient way to get Ripley battling the aliens again. Cameron's films aren't based on logic and substance, they are based on spectacle, so he shoehorned a way for her to go back to the planet and turned her into Wonder Woman once she got there. She became "useful" purely because all the other characters were written as dumb. It's all a bit silly really.
I always thought that a more plausible plot would be to have her go there by force. They had no evidence of what occurred in the first film, so in order to prove her story true they go to investigate despite her objections. Burke could possibly have found information the backed her story but withholds it from everyone as he wants to lay claim to the discovery.