Canadian papers are almost all on his payroll, so they would never report it anyway, unless told to.IT would be perfectly natural under most circumstances but protocol is that he's supposed to be officially in mourning. Somber, sober, etc etc. It's kind of like a 'fun is bad right now' kind of moment. Remember the gov't isn't even supposed to be doing business during those 10 days, there's a federal day off just to mourn. So it looks REALLY bad if you're out partying it up and having a great time.
If this was just a regular state visit this would be a total nothing-burger but when he's there mourning the queen's death? That's a big deal. And it's not a canadian paper that's ripping him for it