As near as I can tell, this position by Dave Winer mostly just exposes his complete lack of understanding of abuse on social media platforms. Users block other users in large part as a barrier to abuse. This is an over-simplification, but blocking abusive users, trolls, or bots not only protects the blocking user but often serves also to protect other users because it keeps the abusers, trolls, and bots from being able to reply to the original user's tweets, and therefore keeps them out of the discussion. I can't think of any other situation where someone would be “[b]locking people from reading things posted publicly”, so it seems like Winer really has just not kept up with how abuse works in the age of social media.
ETA: To make this all the weirder: he's blocked me on Twitter. To quote, erm, Dave Winer: “If it's public it seems everyone should just be able to read it without phony barriers.”