Ethical considerations are briefly discussed at the end of the article -- too briefly, in my opinion.
I wouldn't worry about what could or couldn't be.
Conscious humans are obviously special. But if we grew non-thinking bodies and used them for research, we could vastly accelerate medical science, research and development, and treatments. We could accomplish this with gene knockouts.
It's too "icky" for people, so it hasn't been done.
Or more literally, that they should make for themselves a lab rat, in the way The Thought Emporium is? https://youtu.be/Z_ZGq8Tah0k?si=UI18mJ4k5Xn4OtfD