Because it's completely factually wrong. Go is not AT ALL dynamically typed.

Go is more dynamically typed than Haskell. That is, it leaves nullability to runtime. It leaves parameteric polymorphism to runtime.

Whenever there's a static type that Go cannot express (and there are plenty of those!) it is effectively dynamically typed about that property.

Right, Go doesn't have sum types for example. (Or at least, it didn't. Does it now?)