Obviously not, since Gazzaniga is not explaining his own actions.
He is, among other things, explaining some of his own actions: his actions of explaining his actions.
You seem to have failed to notice the key point. Here's a slight rephrasing of it: "explanations for actions will fail to reflect the actual causes of those actions to the extent that those actions are the results of nonconscious processes."
You ask, does Gazzaniga's explanation apply to explanations made in advance of the actions? The key point I've highlighted answers that question. In particular, your explanation of the actions you plan to take are (well, seem to me to be) the result of conscious processes. You consciously apprehended that you...
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