Fingerprint locks would incapacitate a weapon to everyone save the owner, which pretty much means the Second Amendment is reduced to a self-defense amendment instead of a militia amendment, i. e. an anti-tyranny amendment. Fallen soldiers' weapons would be useless to others.
It's not helpful that the Supreme Court has ruled the right to keep and bear arms an individual right, which plays into the hands of those seeking constitutionality for fingerprint locks.
Can fingerprint condoms be far behind?
Audio of Carson here.