This is one of those things that happens when it happens. It isn't a mental block. Things don't taste the same, appetite isn't the same, favorite foods are not the same or are not actually doable given their dryness, solidness, etc. - so you can't push. LIfe will be a mix of canned supplements with soft, very wet foods for awhile to come. I did only soups and really wet scrambled eggs for a long time, then mashed potatoes with tons of artery clogging butter, canned fruits like peaches in heavy syrup... But he is going to set the pace, and it will eventually all get to his new normal. In the meantime all you can do is count calories and nutrients. See that he keeps both up even if it's via cans of Ensure, Instant Breakfast, or whatever. If he throws it up, deduct calories, give anti nausea drugs, and when they kick in - try again.