I'm not sure it should be allowed, because it is my understanding that Aquinas is not a proper surname, but a patronymic (like "Da Vinci" from Leonardo, or "of Rotterdam" from Erasmus). Isn't that the case?
I think Aquinas should be accepted. People call Leonardo "da Vinci," too. You are technically correct, but Aquinas is commonly accepted on this site. Really cool quiz, though!
Thanks for the feedback!!