It's addressed in the last section of the linked post.
The Cascadia = white nationalism thing was mostly a figment the 70, very few people even know about it, and the imagery is used far far more by liberals in the present era. It is an important thing to be aware of, but it can be addressed down the line. For now, there is no movement, so you need to work with what you got. Rebranding is totally something that should be discussed down the line when there is a party (or other entity) to discuss it.
The thing is that in our region, it's not very much work at all to radicalize people further to the left of what they are. We are in a place (in the major metro regions) where there is a really solid amount of people that need to give up on the US because it as anti-progressive in pretty much every way (as people here already know). Socialists and progressive liberals need to stop viewing themselves as "American" and start seeing the US government as an outside force that is holding us back, because that's what it is.
Even with all that said, regardless of the "Cascadia" brand, the region has a long history of being infested with white nationalism. Cascadian socialists must be well educated on this, and it needs to be a pillar of the movement.
I think you have it right, but also in Portland and Seattle (and other liberal strongholds) I think there is an opportunity right now where the Democrats are clearly just going to keep losing to trump/trump 2.0. Even if they deliver a reprieve every once in a while, anyone who is serious is having their "what is to be done?" moment (why wasn't it in 2016 or any other time? Let's not digress). I'm planning to tighten up a lot of my relationships in the next few weeks before MSM can figure out a way to get people placated again, although that might be really hard for them with Republicans stepping up.