If the original poster had bought or can take advantage of trip cancellation insurance (through a credit card benefit if he/she met the eligibility for that perk), I would suggest he/she do just that.

As far as legal, of course it is. In this case the terms and conditions are spelt before a customer of Aeroplan goes ahead with a redemption. Just because one does not know the particulars if one does not take the time to check does not make it any more or less "legal".