While this data may generally be public in the US, it usually isn't in Canada, and there's an expectation that parties don't publish the data and it is seeded to detect that.
A bigger problem is that people in Canada sign up for this list with the expectation that this data will remain reasonably private so now with this leak you have people who were willing to share their personal information to participate in the democratic process now afraid that their domestic abusers will be able to find them.[0] That really sucks.
There's also the awkward aspect of this in that the Alberta separatists are seemingly backed by American interests.
[0] https://www.cbc.ca/news/canada/edmonton/edmonton-city-counci...