As much as I respect Carmack as a computer graphics expert, I really doubt his competence in machine learning. He doesn't have a single notable paper published. If he really thought that implementing gradient descent and basic stuff in a week long retreat gave him the chops to have serious conversations with AI researchers, he is really deluded.
Unless he can produce something that outdoes stable diffusion, chatgpt, alphago etc he should just hand over technical leadership of his start up to a leading AI researcher. Even Yann Le Cun at Meta is struggling to make any progress and is keeping himself busy by calling every other research labs output pedestrian. We cannot take any of Carmacks AGI predictions seriously, he simply lacks any expertise in the field.