It could be that he does, but I’m not that fussy. From the web: adjective Impossible to comprehend or grasp fully. “inconceivable folly; an inconceivable disaster.” So unlikely or surprising as to have been thought impossible; unbelievable. “an inconceivable victory against all odds.” Not conceivable; incapable of being conceived by the mind; not explicable by the human intellect, or by any known principles or agencies; incomprehensible.
Oat milk is simply rolled oats and water blended together then strained to leave the pulp behind. I looked it up for you. Seems like a waste of oats to me.
“Sedimentary” think sandstone.