So, um, what does "banned" mean if they can continue to post?

As typically used, the term "shadow banned" is a ban without alerting the user that they are banned. That's not the case here. On HN, "banning" means to to have your posts be dead by default. And "banned" is the language 'dang himself used in the message to the user.

There are also numerous bans with no notice at all, just a sudden stream of gray comments that are 0 minutes old.

Yes, there is also autobanning and filtering software. But that is not what happened here.

Wow got banned for saying a 200% tax on gasoline is another example of a government looking to tax the population into poverty and dependence.

The entire web is 1984 now. Crazy couple years

We banned your account for breaking HN's rules, as I explained to you when I banned it: https://news.ycombinator.com/item?id=29127479.

It has nothing to do with your particular statement about gasoline taxes or anything else. You could have made exactly the opposite statement and it would have had the same effect. The deeper issue is that HN is not a site for people who want to defeat their political enemies; it's a site for people who want to have curious conversation and learn from each other. I don't think that's too hard to understand.