I don’t think ”intelligent” is a particularly meaningful concept, and just leads to such confusion as your comment hints at. Do I think a person with locked-in syndrome is still a human being with thoughts, desires and needs? Yes. Do I think we can rank intelligences along an axis where a locked-in person somehow rates lower than a healthy person but higher than a cat? I don’t think so. A cat is very good at being a cat, much better than any human is.

I would also point out that a person with locked-in syndrome still has ”a physical corporeal presence in time and space”, they have carers, relationships, families, histories and lives beyond themselves that are inextricably tied to them as an intelligent being.