The problem is that Google controls the most popular interfaces to consuming HTTP and HTTPS, i.e. their Chrome browser and their search engine. And so Google is in a position where they control how these protocols are consumed, which is the crux of Dave's argument. Google is already discouraging the use of HTTP through warning messages in Chrome and by adjusting search rank algorithms for HTTP sites. Dave's concern is that Google will "turn off" HTTP access in the same way they did with RSS after capturing the market share for consuming RSS feeds and then shutting down Google Reader and removing discoverabilty of RSS feeds in Chrome.
Dave Winer has been around the Web for longer than most and you'd be foolish to write him off as a curmudgeon. Dave is to the open Web what RMS is to FOSS.