I would say this is foolish not even from a Canadian perspective citizens perspective, rather a completely offensive one to one of our closest allies.
For most Canadians they are going to follow exactly what Lumber laid out. From a British perspective, a nation which is going through days of mourning and is known for their stoicism, they have a concept known as time and place. Getting a flight to attend to the funeral of the Monarch on taxpayer dime, to then spend some of that time when your supposed to be mourning or at least representing a mourning nation shows he has no self-control. It is offensive to them. And I would say he owes one of our greatest allies a apology. Especially after partially making something which should have been a show up, do the dance, go home event with only your attendance noted. Into a look at what Trudeau is up to event.
This isn't about a domestic look, it is about how we look internationally, and it isn't a great one.