It would do no such thing. LLMs are neither living nor sentient nor intelligent. The fallacy of computationalism is a failure to read a coarse metaphor as merely analogical. Any correspondence is superficial and limited, and even then, merely correspondence, not identity.

So, the use of human brain cells is different territory. Bioethically speaking, it is illicit to press human body parts (which includes cells) into service for technological ends. They can only licitly enter into service of the integral human whole (such a life-saving transplants). Using them in technology also commoditizes the human body. (The reverse is not the case: it can be licit to use cybernetic devices to restore native function within a human body.)