if she had gone back home and gotten a fiance visa (instead of applying for a COA and then trying the daft strategy of applying in-country for FLR(M), which is not even allowed since she was here as a visitor), they would have been fine and would have been able to get married and get her a spousal visa prior to the rule change.
I like how they say she had "technically" overstayed her visa once their wedding rolled around- it was her choice to stay past her allotted time. If that had happened to me, you can bet I would have hightailed it back to Canada ASAP with fiance in tow before the visa expired and then married there and gotten a spousal visa.
Eh, I can't get too worked up about this. They should have done their research properly.
(I'm not in favour of the 21 age limit in general though, it stinks! But for this particular couple, their current situation is really their own fault.)
Edit (again!): The above assumes the "last March" in the article refers to March 2008 (since if she got here March 2009 chances are her visitor's visa wouldn't have yet expired!) If I'm wrong and she arrived as a visitor *after* the age changes came in, then I have a bit more sympathy, but they still should have done their research to find out the minimum age limits for visas before getting married.