Ryan Reynolds has repeatedly said that he is less than happy with his appearance in the 2011 "Green Lantern" movie - he even admits that he has never seen it.
Ryan Reynolds provided this explanation to EW, highlighting how although there were a lot of people working hard to make Green Lantern successful, Warner Bros was more concerned with releasing the movie rather than making sure the script was perfected before starting. That meant there was never an opportunity to nail down what the movie's tone was supposed to be, making the final product feel generic
So Deadpool, by killing Ryan Reynolds (a Canadian born in Vancouver) before he accepted his role in the Green Lantern, saved the whole country from the embarrassment of a Canadian actor in the movie.