While your example is undeniable, Santa Claus does instruct Harry to get outside Hogwarts before using his playing card portkey, and I’m fairly confident there are other instances to the same effect. It seems that the state of the evidence, both in canon and MoR, roughly amounts to “Portkeys and Apparition do not work within Hogwarts wards except when they do”.
Exactly like that. [sigh]
While your example is undeniable, Santa Claus does instruct Harry to get outside Hogwarts before using his playing card portkey, and I’m fairly confident there are other instances to the same effect. It seems that the state of the evidence, both in canon and MoR, roughly amounts to “Portkeys and Apparition do not work within Hogwarts wards except when they do”.