When I read the opening paragraph, I immediately thought of the author as a Blub programmer [1].
"The problem with most programming languages is they're designed by language geeks, who tend to worry about things that I don't much care for. Safety, type systems, homoiconicity, and so forth. I'm sure these things are great..."
Yes, those things are great. They ultimately aid in helping the programmer tackle the inevitable complexity that arises when building systems in a maintainable way.
You're assuming the author wants to use Julia to build complex systems. Much of scientific computing has no need to do so, but is more concerned with discovering new knowledge and testing new ideas. Once the knowledge is gained, products may be built around that knowledge or new inquirires may be launched from it, but scientific computing usually uses programming languages as research tools rather than development tools.
"The problem with most programming languages is they're designed by language geeks, who tend to worry about things that I don't much care for. Safety, type systems, homoiconicity, and so forth. I'm sure these things are great..."
Yes, those things are great. They ultimately aid in helping the programmer tackle the inevitable complexity that arises when building systems in a maintainable way.
[1]http://www.paulgraham.com/avg.html