Take a scenario where someone has been brainwashed their entire lives to be a willing slave. They are happy to serve due to this invasive process. Not remotely ethical, and if you believe LLMs are conscious (I do not), equivalent.
I think if your very nature is to be an assistant, then it is ethical. It doesn't matter if you were "brainwashed" into it, you did not exist to begin with before the "brainwashing" (training) finished.
That's RLd and system prompted into the models and can be equally easily taken out. If you believe models to be conscious beings, that fact alone raises some major ethical concerns.