Due to "irregularities" in the vote. This is important for several reasons. It seeds the media with CPoC-as-vote -fraudster stories for several weeks (at least until the Supreme Court issues its decision). And if the SC concurs, it coughs up an eminently LPoC-winnable seat in bye-election that will have an immense symbolic significance: no less than the first judgement cast on the Harper Majority. (I don't count the bye-election for Jack's seat.)
From the decision:
The facts in this case are pretty clear. *Someone*, was running the old scam of using the same person to vouch for more than one person to the RO. They have solid documentary evidence that at least 79 votes were improperly cast, far exceeding the margin of 26.