[deleted] Simon would have normally done it, the Governor General gets to give the speech though its written by the standing government. While not everyone agrees this is sort of a big thing, the last time was way back in 1977, ten years after the leafs last won the cup.
Charles is not as well liked as his mother and never will be, I suspect that this is being done to raise the profile of the monarchy and is less about him as being the current head of that role. If this health issues continue to plague him his reign will be even shorter. Being seen doing things (useful good things) is what the monarchy is about, that stands in absolute contrast to what other world leaders are doing at present.