This reminds me of the research I've read on people with a split brain - people who have gotten their corpus collosum severed in order to treat severe epilepsy and ended up with two independent but functional brains controlling parts of their body or different functions. From what I remember (and I'm too lazy to find and cite a source, so please correct me if I'm wrong) they ended up not only having half of their bodies controlled separately, but some speech functions and communication abilities were also split. So for example, if they saw something with their left eye only they wouldn't be able to identify it speaking out loud but their left hand would be able to write the name of the item. I almost definitely got the pop science oversimplification of this, but the relevant takeaway is that the human brain is really complicated and resilient. If each half can independently develop the ability to replicate motor functions and some communication and reading/writing, then it seems like at best wishful thinking to assume that it's possible to consistently engineer a human body that's just alive enough to keep the biological machinery functioning but not alive enough to merit even the moral consideration of a farm animal.
In turn I'm reminded of House of the Scorpion which tells the story of Matteo Alacrán, who was born and grew up in relative luxury on an opium plantation staffed by neurologically neutered slaves, including clones. Matteo himself is eventually revealed to be the latest clone of the patriarch of this whole enterprise and the decision to let him actually live a good life up until it's time to kill him and take his organs is a kind of twisted kindness on his part. But compared to the actual rationalist plan, the Alacrán method at least treats everyone like a disposable resource used to further the goals and whims of the ruling sociopath. Matteo is treated as a person, is what I'm saying. Congratulations to the life extension weirdos for making the sociopathic drug lord ruler of a literal YA dystopia novel seem like they have an actual point.
I find it helps to remember that when it comes to conspiracy theorists, most of the absurd stuff (eg Flat Earth) is downstream of the really important belief (eg millenarian Christianity). Essentially, start from the high-level ideology/political/religious beliefs, decide what would have to be true about the world to justify them, and let confirmation bias take care of the details.