Wow, you found phosfood liquid? I haven't been able to find that in years! woo hoo!
What with the apples, two bottles of GCG and if he does 3 days of phosfood drops, I'd say all he'll have to do is eat a high-fat meal and he'll lose tons of chaffe and crushed up stones without even having to flush! LOL! ;)
but seriously, he's off to a GREAT start and if he's worried have him do the kindler gentler flushes of taking 1 tablespoon of olive oil on an empty stomach every day, then building up to 3 tablespoons. When he gets up to 2-3 tablespoons follow the oil with a lemonade. If all goes well he can certainly handle a flush. :)