You need a certain energy level from the show to maintain the crowd through the extended intermission that you have at a championship game like the Grey Cup. I thought they delivered. And hey, they love Canadian people and apparently our food as well. And their live set easily beat the lip synching and air guitar of the Red Hot Chilli Peppers at the Super Bowl.
Would I prefer a Canadian act? Sure but it's not always a viable option to get one that has enough name recognition, even if it is only recognition across Canada. A number of years ago the Black Eyed Peas performed, also in Vancouver I think, under sponsorship from Best Buy IIRC, and they ended up doing a super bowl halftime as well. For Imagine Dragons I think their label was the one that pushed for them to get the halftime gig and more exposure despite them having already won much acclaim in 2014. If it's a foreign act that gets regular air play on radio stations here in Canada, someone is willing to pay for them to do the halftime show, and they can provide the right atmosphere, then I'm fine by it. I certainly would prefer it over giving the stage to an act like the opening country singer Dallas Smith just because he's Canadian? A set like his would've completely killed the mood in the stadium at half time IMO. Just like Blue Rodeo a couple of years ago. I love the band but it's the wrong type of music for a half time show.