Earlier quoted context omitted.
I think his point is pretty clear in that paragraph: "Music is haunted by the specters of Beethoven and Mozart, even Elvis and John Lennon, with the canon being built around these names that we are told deserve not just celebrating but worshipping. These old, dead white men." The problem is the dead overshadowing the living.
Isn't that the very point of a canon? It takes time for a society to ratify the quality of a cultural artifact, to sift through the chaff and decide on what and who the 'greats' are. Invariably, at any given point in time, most of them are dead. It's possible that in the long run, people will consider Clara Rockmore, Delia Derbyshire, etc. to rank with Beethoven, Mozart, etc. It doesn't seem likely, though. I don't t…
To me, it looks like canonization is more to do with our primate desire to find/create status hierarchies. That seems bad enough when we do it with living people, creating the sort of structures that enable oppression of disfavored groups. But it seems both sillier and worse to do it with dead people.
So I suspect the point of a canon as selected by people of social power is to reinforce the social power structure. Something like what the Catholic church does with canonization. They get to gatekeep "goodness" and control the knowledge and resources that let up-and-comers grow. It becomes another stick to beat the young with, a way to make them "pay their dues" to people holding power.
So my hope is that in the future nobody will waste much time doing fantasy mental tournaments for "greatest" artist between different eras.