Hi and welcome.
I admit I haven’t read the book, am not familiar with his train of thought so I wouldn’t presume to criticise but these are my thoughts: I‘m a great fan of kongs, they do indeed seem to calm an excited pup and are great as a way of distraction when you’re introducing them to a crate or teaching them to stay alone for example but I don’t think I‘d want to use them for meals.
My dog had the small puppy kong to start with, its small and slightly softer which is easier on their milk teeth but you‘d need to fill one several times to serve a meal. They‘re also a bit fiddly to clean out which would concern me a bit with raw meat. I used to fill one with soft liver sausage or cream cheese or similar and give it to Humphrey every night when we went to bed and he stayed in his box, but I then only had to wash it once a day,
Does the author suggest when they can be „weaned off“ ? I knew of a dog who‘d been hand fed as a puppy but then refused to eat from a bowl later on - quite possibly a single case but nevertheless it could give rise to an issue later on maybe.
Slow eating bowls can be useful although I‘ve never needed one, - Humphrey has a deep cocker bowl which keeps his ears out
but he doesn’t gulp his food anyway. I feed raw, which I certainly do recommend.
As I say, there are possibly advantages from feeding from a kong if you have a dog with particular problems or issues so I wouldn’t want to argue against it but in normal circumstances I‘d consider it a bit OTT.
Enjoy your pup!
Jayne