Because of Alexander's studies. He had to take some exams. They had to decide if his studies or OG qualification (4 Nats). I would have decided otherwise, but I do not know the study system in Canada. The date of 4 Nats was known for long time!
This may be the correct translation, but the information is incorrect. The Olympic decision was made at the Czech monitoring session back in August, and it was Mansour/ Ceska, a decision that would not change unless Mansour did not get her passport, which she did. Nicole and Alex did not attend 4 Nats because there had been a college strike in Canada for some time, and so Alex had to do exams. It would not have made any difference if they went, or what the results were, the decision was already made.