<i>Dynamically typed languages are fine for smaller programs and simple web applications, but if you’re building something big, something that will be several millions of lines of code, you really need all the tools you can only get from a statically typed language</i>

From my experience I am only speak to the benefits provided by a statically typed languages as you try modularize the components. That isn't to say that a dynamically typed languages do not provide an alternative or similar benefit, I just do not have large project experience with them.

Not certain how he draws the causation from using agile to the resulting software being modularized and cohesive. It just is a case of correlation on the projects he has worked on.

Both the arguments for dynamic and static languages as presented here are vacuous.