The only people who could benefit from this are Freedom Mobile customers. The biggest windfall will be to Shaw itself. It will take large amounts of data off their wireless network. That means lower infrastructure costs and lower costs for acquiring new wireless frequencies.
Don't know if Shaw will bill Freedom Mobile customers for data over wifi but I suspect they will.* What was free with your own, a friend's or relative's personal wifi could now cost a lot of money when connected to Shaw's access point instead.
*Rogers did something similar by offering phone calls over wifi. The fine print explained that rather than being low cost or free, like most wifi calling services, Rogers bills customers at the full rate as if it was over their own wireless phone network. How many people got sucked in by that I wonder?