Well, he totally forgot about series where the whole girl harem protect a useless powerless MC. Now he is the MC of the world and the harem lol. If she has to act like a guy, the girls would take the news badly when they first see them "training"
Also, he has to accept since denying the offer would make him far from being the "protag's friend"
Also
@Alexander28 imagine the poor cliché named butler now. His organs should be melting from the inside