So there is upstream spam filtering. Thiss seems to contradict what you said: "There is no administrative ostracism. Nobody gets kicked out by brownshirts for expressing their view."

Spam is an expression of views.

Even if this stupid idea were true, in fact nobody prevents Usenet spammers from reaching those who want to be reached.

If you think that spam is a form of expression, and you're interested in it, all you have to do is post a few articles and use your real e-mail address in your From: header.

Then no overbearing NNTP server admin will stand between you and your spammer friends.

How do you know that what was filtered was spam and not wrongthink ?

You've sorta got to trust your admin. If you don't, it's really pretty trivial to put up your own server (you can do it from home, you don't need a VPS, you don't even need constant connectivity) and then you just peer with as many servers as you can -- odds are not ALL of them are filtering those critically important posts calling Biden a pedophile or whatever.

Wrongthink doesn't use a robot to post 20,000 copies?

But it's filtered already, both don't have any copies anymore.