Advise your friend to keep the kitten on wet food for life. No kibble, ever.

Kibble is terrible and leads to a number of health problems, including urinary tract problems (especially in males), kidney problems, and chronic dehydration (which leads to constipation). My 18-year-old was on kibble her whole life and developed chronic kidney failure, which was diagnosed 4 years ago. She has lost over 75% of her kidney function and I attribute it entirely to the kibble diet. She has been on a raw diet since her diagnosis and is doing magnificently well and has not gotten much worse over the last 4 years. Long story short, cats should be fed a grain-free canned formula high in meat protein, which is closer to their normal, natural diet, and no kibble whatsoever. Even the worst canned food is miles better than the "best" high-quality gourmet kibble. Kibble has no benefits at all. It does nothing for their teeth (they are carnivores - their teeth are not designed to grind/crunch).

The main reason is this - cats have a very low thirst drive, as they evolved from desert-dwelling animals, and have changed very little after our "domestication" of them - genetically and physically, they're still pretty much 99% their ancestors. A wild feline is designed to get almost all of its moisture needs out of its prey (meat, blood) and thus has very little "urge" to drink. Even if you think a cat is drinking enough, it's not. Any cat on kibble is in a state of dehydration - they simply do not drink enough to make up for it.

Canned/wet food can be left out for up to 12 hours without going "bad", so there is no reason the kitten cannot eat canned.