@Ezk
First thing first. Different time period. It is only pretty damn recently that physical punishment wasn't regarded as part of raising a kid.
Secondly, gaining prestige and making a political statement ain't always the same. My guess is that they invited the Princess because it is expected to invite royalty to official parties, no matter your political leaning. In fact, not inviting them, even as just a gesture, could be looked as implication of lack of faith towards said royalty. And that would be a very poor political move.
He likely marked as neutral via inviting all sides and not taking favorites, not by excluding certain parties, because ye know, that would be a bloody political statement if I ever saw one.