The Newton example is not about free speech but rather his behaviour, actions, and perceptions of non academics. The example given implies that he would be able to publish, but he wouldn't be able to get a decent (i.e. well promoted, popular) book deal. The example of Newton at the beginning of the article is a little thought experiment where we consider how having odd or off coloured views, or behaving strangely is treated differently by the outside of the academy. Such a thought experiment leads me to think that in the 17th Century it was easier to be a genius, odd, socially awkward mad professor than it is now. I don't know what it was actually like back then, but I do know that today the academy is in the spotlight more than it was when I was in it.