In those experiments, the speaking portion of Joe has no clue what the other side is experiencing. Like they show it to him on the wrong side and say “can you see this?” “No”. Then they ask him to draw it, and to his amazement he does. It’s not just being unable to vocalize certain thoughts - they’re not even there to vocalize at all to that part of the brain. But the other half is happily chugging away with that info