I don't know why anyone would think he is foolish. Listening to his speech at the National Press Club a few days ago it's hard to find many things to disagree with https://www.youtube.com/watch?v=ob-LJqPQEJ4
The linked article was talking about facts, a dissection of various arguments made by Thiel and Trump. Elections aren't about facts (unfortunately?), so they cannot prove anything about whether that article is right or not.