To me as a Canadian, the absurd part is that ordinary people are expected to have "registered" with a party (as opposed to registering with the independent organization that runs elections, like we do; they automate getting most of the voter roll from Revenue Canada, but this requires your explicit consent on the tax form).
I've never once registered with a party in the US. I always check "independent" on my voter registration. But I'm in a state with open primaries, so I can still vote in one or the other primary, even though I'm not registered with the party.
What's the purpose of a primary election? It's to select a party's candidate for a general election. It's not very obvious that this should even be a democratic process, but if it is, why shouldn't party members be the ones selecting their own candidates?
This would kind of be the same as us (I'm Canadian too) registering with the NDP so we can vote for the next leader. But the level of lying on display here is just insane.