Because that's the way they have named their architectures since... For as long as I can remember. Previous generations include: Ampere, Volta, Turing, Kepler, Fermi and more.
This does mark a departure from a convention of only single surnames, and one could surmise as to why that decision was made. Though one might also consult a Falsehoods list, since 'Ada Lovelace' was never $first_name $last_name to begin with, having been derived from something like /(Augusta Ada|Ada Augusta) King \(née Byron\), Countess of Lovelace/