The post is a travelling position, which means Hawking can stay on as an emeritus professor at Cambridge while making regular visits to Canada.
A friend says it's because the Perimeter Institute's new director, Neil Turok, knows Hawking reasonably well. Sounds right.
People here could provide Hawking with a short list of months in which he might be best to avoid the PI. (About six of them actually.)
See also:
Space exploration: Stephen Hawking urges, Boldly go ... but why, exactly?
Stephen Hawking, miffed over science funding cuts, to move to Ontario, Canada?
Who reads popular books on cosmology? Well, almost everyone who actually reads, it seems
Study: Sun not special, therefore alien life should be common?
* hot weather story = It runs over the mast because anyone who could stop the nonsense is on vacation. My all-time favourite was when a Los Angeles Angel took out a seagull while he was playing against the Jays here in Toronto - and was charged with cruelty to animals. And, yes, it was July, and yes, it was pretty hot. The charges were later dropped, of course. Meanwhile, the mayor of Los Angeles offered the mayor of Toronto a trainload of seagulls, if we love them so much. Thanks but no thanks, Your Worship. We're not exactly suffering for lack of gulls here either.
Note: The image of Stephen Hawking is from Wikimedia Commons.