
Nobody won a rally, it’s just a headline that can be parsed to get more than one meaning. I presume this is the correct parsing:
(Subject) [verb] {object}
(Albertans ‘crushed’ by Liberal election win) [rally] {to separate from Canada}
or phrased less ambiguously:
Albertans who were ‘crushed’ by the Liberals winning the election went to a rally about separating from Canada
What do you mean by “Canada’s Joe Biden moment”? Joe Biden had at least 4 years worth of moments.