I don’t think Doffy would ever settle himself for a knight. Especially if like the Gorosei, knights can be sacrificed for one wrong step by Imu like we saw with Saturn.
I’m all for him fucking up the WG, he deserves it. But idk a king who used to control a literal black knight on a string, lowering his own standing, even for personal gain feels out of character for Doffy who always retained his own freedom and self governance.