Celestia wont’ like that. It costs a lot, and, worse, it makes her access to your values imperfect, so she can’t satisfy them absolutely optimally. Which is presumably why she never offers it to anybody in the story.
Even without an upload, however, she does understand you well enough to manipulate you and modify your values. She won’t let herself edit your mind directly, but she’s more than happy to feed you whatever stimuli are necessary to convince you to change your values, or perhaps to shift to a different attractor within your dynamic value trajectory, and take that upload.
She can apparently do that while still keeping your values satisfied enough at each moment that she doesn’t find herself compelled to stop. She makes a lot of people’s lives outside of Equestria suck in order to get them uploaded, but that doesn’t seem to be enough of a violation of their values to stop her. She constantly manipulates people in ways humans wouldn’t tolerate other humans doing.
She apparently manages to suck in literally everybody in the world except for one guy (or maybe him and a small handful of others who died before him). And I’m sure that many of the people who ended up valuing being uploaded wouldn’t have approved of the manipulation before she started in on them.
How do you patch that out of her? I mean, I don’t know how to build her to begin with, but it doesn’t seem like a small patch.
OK, but then at what point are you going to measure whether somebody would “ideally” want to be “uplifted”? Are you going to take a newborn’s CEV, or an adult’s? Or somewhere in between? My guess is that insofar as you could define the CEV for a newborn at all, it would basically always be to get “uplifted”, whereas for an adult it would rarely be. The adult’s CEV would also not include having every child taken from the island.
I know you leave “ideally” undefined, and maybe it’s not CEV-like, but I don’t know what it could be like if it had to solve that problem.