Grammatically speaking, this is a non-issue. English has no gender-neutral pronouns, so traditionally the masculine pronoun has been used for an antecedent that has no stated gender. So in reality the inscription is not at all specific about needing to be a man. It's only specific about the "worthy" part.
Edit: Slight correction. English has gender-neutral pronouns, but they are either plural (they, them) or not acceptable for use in reference to a person (it).