She's basically saying that the fingerprint is as revealing as a passcode in this scenario, which isn't necessarily untrue, but that's not the crux of Fifth Amendment analysis.
The Fifth Amendment protects what's in your head. We've shorthanded it to a right against self-incrimination, but the actual text says that a person cannot "be compelled in any criminal case to be a witness against himself." The general concept is that a person should be not be forced into a position where he has only three options, 1) Lie, 2) Incriminate himself, or 3) be in contempt.
Being compelled to tell the police your passcode is violative of the Fifth Amendment not because it gives the police access to your phone but because it requires you to reveal the contents of your mind, which, in the case of a phone, can be incriminating because it reveals your ability to access the phone. But if you had the passcode tattooed on your finger, there would be no Fifth Amendment problem with the police typing that passcode into the phone. Choosing to use a fingerprint passcode is effectively tattooing your passcode on your finger.
The textbook example is a wall safe that can be opened by a combination lock or a key. The police cannot compel you to tell them the combination. They also cannot compel you to tell them the location of the key. But if the key is in your pocket, they can take the key and use it to open the safe. The first two reveal the contents of your mind; the last does not.