I understand why you wouldn't want to make your friend feel that you doubt her story. But when you do eventually get around to talking with her about it, you don't have to make it sound like you believe she was scammed. Even if the kitten isn't a Bengal, that wouldn't necessarily mean it was a scam. Maybe the person who raised the kittens decided their cat was a Bengal based on pictures they saw online, and then thought it was accurate to advertise the cat's kittens as Bengals. Most people who misrepresent kittens' breeds are just misinformed, and don't intend to scam others.
It's also theoretically possible, I guess, that the kitten could be a pet quality Bengal, going through the "fuzzy" developmental stage during which the coat pattern is not very clear... although it's really not typical of a Bengal to have that type of broken mackerel coat pattern... and at this time it just looks like an adorable little domestic shorthair kitten.
In any case, even if the kitten isn't a Bengal, that wouldn't mean that the kitten is any less special! Domestic shorthair cats are just as wonderful pets as any pedigreed cat. Sometimes, for example with pet insurance, it can even be advantageous if your cat is identified as a domestic shorthair rather than a pedigreed cat (especially a hybrid breed like a Bengal).