One potential problem with that approach is that biometric systems can conceivably be fooled, by a shapeshifting organism or with another way to duplicate the biometrics. As a comic example, the original Cyborg Superman (Hank Henshaw) has organic parts that are a genetic copy of Superman's DNA, because Hank at one point controlled the ship that brought Clark to Earth. That means that he not only gained most of Superman's advanced powers in a yellow sun, but that he can bypass biometric security on places like the Fortress of Solitude that would normally block someone who isn't Kryptonian or has special access. Genetically speaking, Hank is identical to Clark. Plus he can also control most forms of technology with his cyborg elements, so there's that advantage.