The Crusade isn't bad because it's unfair to Phantaria (life's unfair deal with it), but because it's an all around ridiculous idea. Defending Terran could be done by sending two nobles to sit in Chateau Saffalore until judgement day. Even without interference Phantaria would have a difficult time scaling Terran's walls.
What this Crusade shows is that the people implementing it attach no value to the concept. It is not a mighty weapon to be wielded against foes of great strength (Aurvandil) or even villains of mediocre merit (Asylon), no, it is a blunt instrument to be brought down upon any weakling realm that gives a dirty look. It's laughable.
But that is not the only negative aspect of this event. Another would be that it demonstrates how futile it is for non-SA realms to interact with SA realms. If they do, they get squashed. Sounds like a good position for SA to be in from a Darwinian view, but in terms of entertainment it leaves something to be desired. It would of course be ideal for SA if they had a host of legitimate threats surrounding them to occupy their interests', as not only would it provide warfare for it's cobweb covered legions, but it would also provide added seriousness for their internal diplomacy, so that they wouldn't have to indulge themselves by declaring crusades on realms with two functional regions every so often.