There’s a difference between “valid concern” and “any possibility.” LLMs are possibly sentient in the same sense that rocks are, technically we haven’t identified where the sentience comes from. So maybe it is in there.

Personally, I’m coming around to the spiritual belief that rocks might be sentient, but I don’t expect other people to treat their treatment of rocks as a valid problem and also it isn’t obvious what the ethical treatment of a rock is.