I disagree substantially with this argument. As a letter written by UPEI professor Henry Srebrnik points out, nearly all modern nation-states and nationalisms are ethnic in origin.
Lysiane Gagnon is correct that it is "the presence, in Quebec, of six million French Canadians [that] is the only reason Quebeckers think of the province as a nation." This, to her, makes Quebec nationalism "ethnic," and therefore unsavoury, despite the fact that other citizens of the province, not descended from the original French settlement, have full legal and political rights.
Of course, by applying her definition, almost all European states are also "ethnic" in origin. Are they therefore not legitimate? Perhaps Ireland ought to be reunited with the United Kingdom, Norway with Sweden, and the Humpty Dumpty known as Yugoslavia be put together again?
It may not be necessary for an ethnically based nation to demand independence -- so far, the Catalans and Scots have not taken this road -- but it does not in any way make either of them less of a nation than is France or Poland.
Poland, it should be noted, ceased being a state for more than a century. It certainly remained a nation.
Even the nationalism of such states as the United States, France, and Argentina, where national identities are generally founded on the principle that nationality is--or at least was--chosen, I'd argue, is based on certain factors which are fundamentally ethnic (the population descended from 17th century English settlements on the Atlantic seaboard, the Romance-speakers of northwestern Europe, the Iberian and other settlers in the Southern Cone). Simon Langlois' long essay "Canadian Identity: A Francophone Perspective" makes it clear that the old French Canadian identity, based on "ties of descent, lineage, and blood relationship," has shattered, and that Québec and Acadia have gone their separate ways, evolving into self-consciously modern and bureaucratic-rational societies. It only makes sense that, in these circumstances, the French Canadians living in Québec would come to identify themselves as a distinctive population. Saying that they shouldn't have done that, or that they should go back to that, is silly. Gregory D. Morrow in Agora Vox ("Why Recognizing Quebec as a Nation is Problematic") misses the point somewhat when he says that, by many of the same criteria, Alberta and Newfoundland could recognize themselves as nations: Yes, they could if they want to.
As for the presence of minorities and diasporas, all that I can say is that nations and nation-states have ragged boundaries. Look at Spain's Catalonia, making its own accession to nationhood, even though barely more than half of the world's Catalanophones live in Catalonia proper, and even though perhaps half of Catalonia's population speaks natively a language other than Catalan. This is good and in fitting with the historically rather open nature of Catalonian nationalism, founded--at least in theory--not on principles of ethnic descent but rather on the basis of an individual's voluntary adherence to the nation. I'd think that the transition from a French Canadian nationalism marked by bloodlines to a Québécois nationalism founded on similar principles to the Catalonian would be something that most people would welcome.