"... anything that allows arbitrary devices to pretend to be an iPhone and sync jeopardizes email account information--which can be synced to the iPhone--and is a security flaw."

Since we are talking about USB ids here, pretending to be an iPhone would open a "security flaw" only when they have physical access to the computer iPhone's being synced with.

In which case a person already can do whatever they like with it. E.g., just copy your entire hard drive.