As a Canadian I'd also say that having such a party is a huge boon to the country. Separatists are going to separatist - your choice, as a nation, is whether to allow them to organize and have their voices heard within the system of politics or whether to force them to resort to violence and underground organization. Those underground separatist groups will always exist but giving formal political representation to the desire for separation (even if it isn't granted) can help defuse extremism and provide better methods for airing grievances.

The modern BQ is much more tame than the BQ of thirty years prior - they've mainly morphed into a party focused on franophone rights within Canada and the maintenance of QC labor rights. So while they specifically no longer represent that separatist movement as directly there are other groups focused on prairie separatism that are a better modern parallel.