Sounds like the captain wasn't all that wrong. The Air Canada jet was ahead of the CanJet when they started down, the controller obviously never issued speeds to keep that sequence and when a 60kt overtake happened, instead of asking the front aircraft to go faster and the back to slow, she decided to turn the front aircraft behind the back one. Basically, she decided to swap the order, without giving the Air Canada a chance to speed up to match the back aircraft. That should have happened much further back then 8 miles when she turned them. Then, as is typical with planes turning final, the CanJet slowed to 170 or less, and the Air Canada, still never issued a speed, was now overtaking the aircraft they were turned behind, and now they are being told to slow. The CanJet should have been turned and slowed to stay behind the Air Canada. It was an A319 vs a B737 so similar jets, easily could have been told to maintain speeds that would have kept them separated all the way in the descent.