Hi, co-author here. We actually touched upon this subject in the article: 'Tip: Don’t prove what you don’t need to prove' and surrounding text. Also previous comment by Yannick: https://news.ycombinator.com/item?id=31980126
And thanks for writing this up, by the way. Having people less familiar with formal methods try and write up their experiences is, I think, much more effective at letting people in than having experts try and write tutorials.