There is too much on this unpleasant affair to discuss. Of course, the spa thing is a big PR mistake from every point of view. It has nothing to do with the fact that they would not have been that useful in Brussels anyway. They should have cancelled the trip and stayed in Brussels, IMO. And the King should probably have spoken to the Nation when the situation became so worrying (I know that depends on the Government but anyway massive PR fail from all parts).
Then again, P&M have been done a flawless job since they became monarchs, and everybody makes mistakes. They are not the first royals to fail this way nor will they be the last ones. I expected from them to recognize their fault in what it takes and go on.
But. I think it's not a mistake what defines a royal, or a person, for that matter, since we all make mistakes. It's the reaction to your own mistake what does. And you have this:
I know Belgium is not Spain and so I don't expect Philippe to apologize in public à la Juan Carlos, but comment nothing at all would have been a thousand times more appropriate that insinuating that the anger caused for your own mistake is a "futility".
That single quote speaks a lot more to me (and not in a good way) than the supposed scandal by itself.